diff --git a/include/villas/io/csv.h b/include/villas/io/csv.h
index 993305664..c7f2a1027 100644
--- a/include/villas/io/csv.h
+++ b/include/villas/io/csv.h
@@ -32,4 +32,4 @@ struct sample;
 
 int csv_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags);
 
-int csv_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags);
+int csv_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags);
diff --git a/include/villas/io/json.h b/include/villas/io/json.h
index 045a1201e..8274732bc 100644
--- a/include/villas/io/json.h
+++ b/include/villas/io/json.h
@@ -28,8 +28,8 @@
 
 int json_pack_sample(json_t **j, struct sample *s, int flags);
 
-int json_unpack_sample(json_t *j, struct sample *s, int *flags);
+int json_unpack_sample(json_t *j, struct sample *s, int flags);
 
 int json_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags);
 
-int json_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags);
+int json_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags);
diff --git a/include/villas/io/msg.h b/include/villas/io/msg.h
index 9c520d06d..508b5be68 100644
--- a/include/villas/io/msg.h
+++ b/include/villas/io/msg.h
@@ -68,4 +68,4 @@ int msg_from_sample(struct msg *msg, struct sample *smp);
 int msg_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], unsigned cnt, int flags);
 
 /** Read struct sample's from buffer \p buf into samples \p smps. */
-int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags);
+int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags);
diff --git a/include/villas/io/raw.h b/include/villas/io/raw.h
index 797503fed..9fa5d04cb 100644
--- a/include/villas/io/raw.h
+++ b/include/villas/io/raw.h
@@ -34,7 +34,7 @@ enum raw_flags {
 	RAW_BE_INT	= (1 << 17), /**< Byte-order for integer data: big-endian if set. */
 	RAW_BE_FLT	= (1 << 18), /**< Byte-order for floating point data: big-endian if set. */
 	RAW_BE_HDR	= (1 << 19), /**< Byte-order for fake header fields: big-endian if set. */
-	
+
 	/** Byte-order for all fields: big-endian if set. */
 	RAW_BE		= RAW_BE_INT | RAW_BE_FLT | RAW_BE_HDR,
 
@@ -57,4 +57,4 @@ enum raw_flags {
 int raw_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], unsigned cnt, int flags);
 
 /** Read struct sample's from buffer \p buf into samples \p smps. */
-int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags);
+int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags);
diff --git a/include/villas/io/villas.h b/include/villas/io/villas.h
index 94aadc40d..34d248013 100644
--- a/include/villas/io/villas.h
+++ b/include/villas/io/villas.h
@@ -33,4 +33,4 @@ int villas_scan(struct io *io, struct sample *smps[], unsigned cnt);
 
 int villas_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags);
 
-int villas_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags);
+int villas_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags);
diff --git a/include/villas/io_format.h b/include/villas/io_format.h
index 7bca9954f..599acd34c 100644
--- a/include/villas/io_format.h
+++ b/include/villas/io_format.h
@@ -30,12 +30,6 @@ struct sample;
 struct io;
 
 enum io_format_flags {
-	IO_FORMAT_NANOSECONDS	= (1 << 0), /**< Include nanoseconds in output. */
-	IO_FORMAT_OFFSET	= (1 << 1), /**< Include offset / delta between received and send timestamps. */
-	IO_FORMAT_SEQUENCE	= (1 << 2), /**< Include sequence number in output. */
-	IO_FORMAT_VALUES	= (1 << 3), /**< Include values in output. */
-	IO_FORMAT_ALL		= 15,       /**< Enable all output options. */
-
 	IO_FORMAT_BINARY	= (1 << 8)
 };
 
@@ -70,7 +64,7 @@ struct io_format {
 	 * @see rewind()
 	 */
 	void (*rewind)(struct io *io);
-	
+
 	/** Get a file descriptor which can be used with select / poll */
 	int (*fd)(struct io *io);
 
@@ -89,13 +83,13 @@ struct io_format {
 	 */
 
 	/** @see io_format_sscan */
-	int (*sscan)(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags);
+	int (*sscan)(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags);
 
 	/** @see io_format_sprint */
 	int (*sprint)(char *buf, size_t len, size_t *wbytes, struct sample *smps[], unsigned cnt, int flags);
 
 	/** @see io_format_fscan */
-	int (*fscan)(FILE *f, struct sample *smps[], unsigned cnt, int *flags);
+	int (*fscan)(FILE *f, struct sample *smps[], unsigned cnt, int flags);
 
 	/** @see io_format_fprint */
 	int (*fprint)(FILE *f, struct sample *smps[], unsigned cnt, int flags);
@@ -119,7 +113,7 @@ struct io_format * io_format_lookup(const char *name);
  * @retval >=0		The number of samples which have been parsed from \p buf and written into \p smps.
  * @retval <0		Something went wrong.
  */
-int io_format_sscan(struct io_format *fmt, char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags);
+int io_format_sscan(struct io_format *fmt, char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags);
 
 /** Print \p cnt samples from \p smps into buffer \p buf of length \p len.
  *
@@ -139,7 +133,7 @@ int io_format_sprint(struct io_format *fmt, char *buf, size_t len, size_t *wbyte
  * @retval >=0		The number of samples which have been parsed from \p f and written into \p smps.
  * @retval <0		Something went wrong.
  */
-int io_format_fscan(struct io_format *fmt, FILE *f, struct sample *smps[], unsigned cnt, int *flags);
+int io_format_fscan(struct io_format *fmt, FILE *f, struct sample *smps[], unsigned cnt, int flags);
 
 /** Print \p cnt samples from \p smps to stream \p f.
  *
diff --git a/include/villas/sample.h b/include/villas/sample.h
index 7c6d88925..662d07704 100644
--- a/include/villas/sample.h
+++ b/include/villas/sample.h
@@ -52,11 +52,24 @@ enum sample_data_format {
 	SAMPLE_DATA_FORMAT_INT   = 1
 };
 
+/** Parts of a sample that can be serialized / de-serialized by the IO formats */
+enum sample_has {
+	SAMPLE_ORIGIN		= (1 << 0), /**< Include nanoseconds in output. */
+	SAMPLE_RECEIVED		= (1 << 1), /**< Include nanoseconds in output. */
+	SAMPLE_OFFSET		= (1 << 2),
+	SAMPLE_SOURCE		= (1 << 3),
+	SAMPLE_ID		= (1 << 4),
+	SAMPLE_SEQUENCE		= (1 << 5), /**< Include sequence number in output. */
+	SAMPLE_VALUES		= (1 << 6), /**< Include values in output. */
+	SAMPLE_FORMAT		= (1 << 7),
+	SAMPLE_ALL		= (1 << 7) - 1, /**< Enable all output options. */
+};
+
 struct sample {
 	int sequence; /**< The sequence number of this sample. */
 	int length;   /**< The number of values in sample::values which are valid. */
 	int capacity; /**< The number of values in sample::values for which memory is reserved. */
-	
+
 	int id;
 
 	atomic_int refcnt;   /**< Reference counter. */
@@ -70,6 +83,8 @@ struct sample {
 		struct timespec sent;		/**< The point in time when this data was send for the last time. */
 	} ts;
 
+	int has;
+
 	/** A long bitfield indicating the number representation of the first 64 values in sample::data[].
 	 *
 	 * @see sample_data_format
diff --git a/lib/hooks/fix_ts.c b/lib/hooks/fix_ts.c
deleted file mode 100644
index 4e6d8f6b1..000000000
--- a/lib/hooks/fix_ts.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/** Fix timestamp hook.
- *
- * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
- * @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
- * @license GNU General Public License (version 3)
- *
- * VILLASnode
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *********************************************************************************/
-
-/** @addtogroup hooks Hook functions
- * @{
- */
-
-#include "hook.h"
-#include "plugin.h"
-#include "timing.h"
-#include "sample.h"
-
-int fix_ts_read(struct hook *h, struct sample *smps[], unsigned *cnt)
-{
-	struct timespec now;
-
-	now = time_now();
-
-	for (int i = 0; i < *cnt; i++) {
-		/* Check for missing receive timestamp
-		 * Usually node_type::read() should update the receive timestamp.
-		 * An example would be to use hardware timestamp capabilities of
-		 * modern NICs.
-		 */
-		if ((smps[i]->ts.received.tv_sec ==  0 && smps[i]->ts.received.tv_nsec ==  0) ||
-		    (smps[i]->ts.received.tv_sec == -1 && smps[i]->ts.received.tv_nsec == -1))
-			smps[i]->ts.received = now;
-
-		/* Check for missing origin timestamp */
-		if ((smps[i]->ts.origin.tv_sec ==  0 && smps[i]->ts.origin.tv_nsec ==  0) ||
-		    (smps[i]->ts.origin.tv_sec == -1 && smps[i]->ts.origin.tv_nsec == -1))
-			smps[i]->ts.origin = now;
-	}
-
-	return 0;
-}
-
-static struct plugin p = {
-	.name		= "fix_ts",
-	.description	= "Update timestamps of sample if not set",
-	.type		= PLUGIN_TYPE_HOOK,
-	.hook		= {
-		.flags	= HOOK_NODE | HOOK_BUILTIN,
-		.priority = 0,
-		.read	= fix_ts_read,
-	}
-};
-
-REGISTER_PLUGIN(&p)
-
-/** @} */
diff --git a/lib/hooks/print.c b/lib/hooks/print.c
index 70645a4d3..1107d6358 100644
--- a/lib/hooks/print.c
+++ b/lib/hooks/print.c
@@ -51,7 +51,7 @@ static int print_start(struct hook *h)
 	struct print *p = h->_vd;
 	int ret;
 
-	ret = io_init(&p->io, p->format, IO_FORMAT_ALL);
+	ret = io_init(&p->io, p->format, SAMPLE_ALL);
 	if (ret)
 		return ret;
 
diff --git a/lib/io.c b/lib/io.c
index 261edd48c..f53d1b0ec 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -59,7 +59,7 @@ int io_stream_open(struct io *io, const char *uri)
 	if (uri) {
 		if (aislocal(uri)) {
 			io->mode = IO_MODE_STDIO;
-			
+
 			io->stdio.output = fopen(uri, "a+");
 			if (io->stdio.output == NULL)
 				return -1;
@@ -87,7 +87,7 @@ int io_stream_open(struct io *io, const char *uri)
 		io->stdio.input  = stdin;
 		io->stdio.output = stdout;
 	}
-	
+
 	if (io->mode == IO_MODE_STDIO) {
 		ret = setvbuf(io->stdio.input, NULL, _IOLBF, BUFSIZ);
 		if (ret)
@@ -187,7 +187,7 @@ int io_stream_fd(struct io *io)
 		case IO_MODE_CUSTOM:
 			return -1;
 	}
-	
+
 	return -1;
 }
 
@@ -244,7 +244,7 @@ int io_print(struct io *io, struct sample *smps[], unsigned cnt)
 		FILE *f = io->mode == IO_MODE_ADVIO
 				? io->advio.output->file
 				: io->stdio.output;
-		
+
 		//flockfile(f);
 
 		if (io->_vt->fprint)
@@ -259,7 +259,7 @@ int io_print(struct io *io, struct sample *smps[], unsigned cnt)
 		}
 		else
 			ret = -1;
-		
+
 		//funlockfile(f);
 	}
 
@@ -279,37 +279,35 @@ int io_scan(struct io *io, struct sample *smps[], unsigned cnt)
 		FILE *f = io->mode == IO_MODE_ADVIO
 				? io->advio.input->file
 				: io->stdio.input;
-		
+
 		//flockfile(f);
-		
-		int flags = io->flags;
 
 		if (io->_vt->fscan)
-			return io->_vt->fscan(f, smps, cnt, &flags);
+			return io->_vt->fscan(f, smps, cnt, io->flags);
 		else if (io->_vt->sscan) {
 			size_t bytes, rbytes;
 			char buf[4096];
 
 			bytes = fread(buf, 1, sizeof(buf), f);
 
-			ret = io->_vt->sscan(buf, bytes, &rbytes, smps, cnt, &flags);
+			ret = io->_vt->sscan(buf, bytes, &rbytes, smps, cnt, io->flags);
 		}
 		else
 			ret = -1;
-		
+
 		//funlockfile(f);
 	}
-	
+
 	return ret;
 }
 
 struct io_format * io_format_lookup(const char *name)
 {
 	struct plugin *p;
-	
+
 	p = plugin_lookup(PLUGIN_TYPE_IO, name);
 	if (!p)
 		return NULL;
-	
+
 	return &p->io;
 }
diff --git a/lib/io/csv.c b/lib/io/csv.c
index aae43a75b..a55332b3c 100644
--- a/lib/io/csv.c
+++ b/lib/io/csv.c
@@ -30,12 +30,12 @@
 
 size_t csv_sprint_single(char *buf, size_t len, struct sample *s, int flags)
 {
-	size_t off = snprintf(buf, len, "%ld", s->ts.origin.tv_sec);
-	
-	if (flags & IO_FORMAT_NANOSECONDS)
-		off += snprintf(buf + off, len - off, "%c%09llu", CSV_SEPARATOR, (unsigned long long) s->ts.origin.tv_nsec);
+	size_t off = 0;
 
-	if (flags & IO_FORMAT_SEQUENCE)
+	if (flags & SAMPLE_ORIGIN)
+		off += snprintf(buf + off, len - off, "%ld%c%09ld", s->ts.origin.tv_sec, CSV_SEPARATOR, s->ts.origin.tv_nsec);
+
+	if (flags & SAMPLE_SEQUENCE)
 		off += snprintf(buf + off, len - off, "%c%u", CSV_SEPARATOR, s->sequence);
 
 	for (int i = 0; i < s->length; i++) {
@@ -50,31 +50,37 @@ size_t csv_sprint_single(char *buf, size_t len, struct sample *s, int flags)
 	}
 
 	off += snprintf(buf + off, len - off, "\n");
-	
+
 	return off;
 }
 
-size_t csv_sscan_single(const char *buf, size_t len, struct sample *s, int *flags)
+size_t csv_sscan_single(const char *buf, size_t len, struct sample *s, int flags)
 {
 	const char *ptr = buf;
 	char *end;
 
+	s->has = 0;
+
 	s->ts.origin.tv_sec = strtoul(ptr, &end, 10);
 	if (end == ptr || *end == '\n')
 		goto out;
-	
+
 	ptr = end;
-	
+
 	s->ts.origin.tv_nsec = strtoul(ptr, &end, 10);
 	if (end == ptr || *end == '\n')
 		goto out;
-	
+
 	ptr = end;
-	
+
+	s->has |= SAMPLE_ORIGIN;
+
 	s->sequence = strtoul(ptr, &end, 10);
 	if (end == ptr || *end == '\n')
 		goto out;
 
+	s->has |= SAMPLE_SEQUENCE;
+
 	for (ptr  = end, s->length = 0;
 	                 s->length < s->capacity;
 	     ptr  = end, s->length++) {
@@ -94,11 +100,12 @@ size_t csv_sscan_single(const char *buf, size_t len, struct sample *s, int *flag
 		if (end == ptr)
 			goto out;
 	}
-	
+
 out:	if (*end == '\n')
 		end++;
 
-	s->ts.received = time_now();
+	if (s->length > 0)
+		s->has |= SAMPLE_VALUES;
 
 	return end - buf;
 }
@@ -110,21 +117,21 @@ int csv_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], uns
 
 	for (i = 0; i < cnt && off < len; i++)
 		off += csv_sprint_single(buf + off, len - off, smps[i], flags);
-	
+
 	if (wbytes)
 		*wbytes = off;
 
 	return i;
 }
 
-int csv_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int csv_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
 	int i;
 	size_t off = 0;
 
 	for (i = 0; i < cnt && off < len; i++)
 		off += csv_sscan_single(buf + off, len - off, smps[i], flags);
-	
+
 	if (rbytes)
 		*rbytes = off;
 
@@ -139,13 +146,13 @@ int csv_fprint_single(FILE *f, struct sample *s, int flags)
 	ret = csv_sprint_single(line, sizeof(line), s, flags);
 	if (ret < 0)
 		return ret;
-	
+
 	fputs(line, f);
 
 	return 0;
 }
 
-int csv_fscan_single(FILE *f, struct sample *s, int *flags)
+int csv_fscan_single(FILE *f, struct sample *s, int flags)
 {
 	char *ptr, line[4096];
 
@@ -172,7 +179,7 @@ int csv_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 	return i;
 }
 
-int csv_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags)
+int csv_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 {
 	int ret, i;
 	for (i = 0; i < cnt; i++) {
diff --git a/lib/io/json.c b/lib/io/json.c
index f9b9374c7..bf21abebb 100644
--- a/lib/io/json.c
+++ b/lib/io/json.c
@@ -33,14 +33,14 @@ int json_pack_sample(json_t **j, struct sample *smp, int flags)
 			"origin",   smp->ts.origin.tv_sec,   smp->ts.origin.tv_nsec,
 			"received", smp->ts.received.tv_sec, smp->ts.received.tv_nsec,
 			"sent",     smp->ts.sent.tv_sec,     smp->ts.sent.tv_nsec);
-	
-	if (flags & IO_FORMAT_SEQUENCE) {
+
+	if (flags & SAMPLE_SEQUENCE) {
 		json_t *json_sequence = json_integer(smp->sequence);
-			
+
 		json_object_set(json_smp, "sequence", json_sequence);
 	}
-	
-	if (flags & IO_FORMAT_VALUES) {
+
+	if (flags & SAMPLE_VALUES) {
 		json_t *json_data = json_array();
 
 		for (int i = 0; i < smp->length; i++) {
@@ -50,10 +50,10 @@ int json_pack_sample(json_t **j, struct sample *smp, int flags)
 
 			json_array_append(json_data, json_value);
 		}
-		
+
 		json_object_set(json_smp, "data", json_data);
 	}
-	
+
 	*j = json_smp;
 
 	return 0;
@@ -63,23 +63,23 @@ int json_pack_samples(json_t **j, struct sample *smps[], unsigned cnt, int flags
 {
 	int ret;
 	json_t *json_smps = json_array();
-	
+
 	for (int i = 0; i < cnt; i++) {
 		json_t *json_smp;
-		
+
 		ret = json_pack_sample(&json_smp, smps[i], flags);
 		if (ret)
 			break;
-		
+
 		json_array_append(json_smps, json_smp);
 	}
-	
+
 	*j = json_smps;
-	
+
 	return cnt;
 }
 
-int json_unpack_sample(json_t *json_smp, struct sample *smp, int *flags)
+int json_unpack_sample(json_t *json_smp, struct sample *smp, int flags)
 {
 	int ret;
 	json_t *json_data, *json_value;
@@ -95,16 +95,17 @@ int json_unpack_sample(json_t *json_smp, struct sample *smp, int *flags)
 
 	if (ret)
 		return ret;
-	
+
 	if (!json_is_array(json_data))
 		return -1;
 
+	smp->has = SAMPLE_ORIGIN | SAMPLE_RECEIVED | SAMPLE_SEQUENCE;
 	smp->length = 0;
 
 	json_array_foreach(json_data, i, json_value) {
 		if (i >= smp->capacity)
 			break;
-		
+
 		switch (json_typeof(json_value)) {
 			case JSON_REAL:
 				smp->data[i].f = json_real_value(json_value);
@@ -122,19 +123,22 @@ int json_unpack_sample(json_t *json_smp, struct sample *smp, int *flags)
 
 		smp->length++;
 	}
-	
+
+	if (smp->length > 0)
+		smp->has |= SAMPLE_VALUES;
+
 	return 0;
 }
 
-int json_unpack_samples(json_t *json_smps, struct sample *smps[], unsigned cnt, int *flags)
+int json_unpack_samples(json_t *json_smps, struct sample *smps[], unsigned cnt, int flags)
 {
 	int ret;
 	json_t *json_smp;
 	size_t i;
-	
+
 	if (!json_is_array(json_smps))
 		return -1;
-	
+
 	json_array_foreach(json_smps, i, json_smp) {
 		if (i >= cnt)
 			break;
@@ -167,7 +171,7 @@ int json_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], un
 	return ret;
 }
 
-int json_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int json_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
 	int ret;
 	json_t *json;
@@ -182,7 +186,7 @@ int json_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], uns
 		return ret;
 
 	json_decref(json);
-	
+
 	if (rbytes)
 		*rbytes = err.position;
 
@@ -208,7 +212,7 @@ int json_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 	return i;
 }
 
-int json_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags)
+int json_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 {
 	int i, ret;
 	json_t *json;
diff --git a/lib/io/msg.c b/lib/io/msg.c
index a213d37eb..cfc2028f8 100644
--- a/lib/io/msg.c
+++ b/lib/io/msg.c
@@ -80,12 +80,11 @@ int msg_to_sample(struct msg *msg, struct sample *smp)
 	if (ret)
 		return -1;
 
+	smp->has = SAMPLE_ORIGIN | SAMPLE_SEQUENCE | SAMPLE_VALUES | SAMPLE_ID;
 	smp->length = MIN(msg->length, smp->capacity);
 	smp->sequence = msg->sequence;
 	smp->id = msg->id;
 	smp->ts.origin = MSG_TS(msg);
-	smp->ts.received.tv_sec  = -1;
-	smp->ts.received.tv_nsec = -1;
 	smp->format = 0;
 
 	for (int i = 0; i < smp->length; i++) {
@@ -124,7 +123,7 @@ int msg_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], uns
 	for (i = 0; i < cnt; i++) {
 		struct msg *msg = (struct msg *) ptr;
 		struct sample *smp = smps[i];
-		
+
 		if (ptr + MSG_LEN(smp->length) > buf + len)
 			break;
 
@@ -140,18 +139,18 @@ int msg_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], uns
 
 		ptr += MSG_LEN(smp->length);
 	}
-	
+
 	if (wbytes)
 		*wbytes = ptr - buf;
 
 	return i;
 }
 
-int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
 	int ret, i = 0, values;
 	char *ptr = buf;
-	
+
 	if (len % 4 != 0) {
 		warn("Packet size is invalid: %zd Must be multiple of 4 bytes.", len);
 		return -1;
@@ -170,16 +169,16 @@ int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 			warn("Invalid msg received: reason=1");
 			break;
 		}
-		
-		values = (*flags & MSG_WEB) ? msg->length : ntohs(msg->length);
-		
+
+		values = (flags & MSG_WEB) ? msg->length : ntohs(msg->length);
+
 		/* Check if remainder of message is in buffer boundaries */
 		if (ptr + MSG_LEN(values) > buf + len) {
 			warn("Invalid msg received: reason=2, msglen=%zu, len=%zu, ptr=%p, buf=%p, i=%u", MSG_LEN(values), len, ptr, buf, i);
 			break;
 		}
 
-		if (*flags & MSG_WEB)
+		if (flags & MSG_WEB)
 			;
 		else
 			msg_ntoh(msg);
@@ -192,7 +191,7 @@ int msg_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 
 		ptr += MSG_LEN(smp->length);
 	}
-	
+
 	if (rbytes)
 		*rbytes = ptr - buf;
 
diff --git a/lib/io/raw.c b/lib/io/raw.c
index 43144b2fc..c164d8f61 100644
--- a/lib/io/raw.c
+++ b/lib/io/raw.c
@@ -23,7 +23,6 @@
 #include "sample.h"
 #include "plugin.h"
 #include "utils.h"
-#include "compat.h"
 #include "io/raw.h"
 
 /** Convert float to host byte order */
@@ -61,14 +60,14 @@ int raw_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], uns
 
 	int i, o = 0;
 	size_t nlen;
-	
+
 	int8_t  *i8  = (void *) buf;
 	int16_t *i16 = (void *) buf;
 	int32_t *i32 = (void *) buf;
 	int64_t *i64 = (void *) buf;
 	float   *f32 = (void *) buf;
 	double  *f64 = (void *) buf;
-	
+
 	int bits = 1 << (flags >> 24);
 
 	for (i = 0; i < cnt; i++) {
@@ -128,12 +127,12 @@ int raw_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[], uns
 	return i;
 }
 
-int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
 	/* The raw format can not encode multiple samples in one buffer
 	 * as there is no support for framing. */
 	struct sample *smp = smps[0];
-	
+
 	int8_t  *i8  = (void *) buf;
 	int16_t *i16 = (void *) buf;
 	int32_t *i32 = (void *) buf;
@@ -141,15 +140,15 @@ int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 	float   *f32 = (void *) buf;
 	double  *f64 = (void *) buf;
 
-	int off, bits = 1 << (*flags >> 24);
-	
+	int off, bits = 1 << (flags >> 24);
+
 	smp->length = len / (bits / 8);
-	
-	if (*flags & RAW_FAKE) {
+
+	if (flags & RAW_FAKE) {
 		off = 3;
-		
+
 		if (smp->length < off) {
-//			warn("Node %s received a packet with no fake header. Skipping...", node_name(n));
+			warn("Received a packet with no fake header. Skipping...");
 			return 0;
 		}
 
@@ -157,21 +156,24 @@ int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 
 		switch (bits) {
 			case 32:
-				smp->sequence          = SWAP_INT_TOH(*flags & RAW_BE_HDR, 32, i32[0]);
-				smp->ts.origin.tv_sec  = SWAP_INT_TOH(*flags & RAW_BE_HDR, 32, i32[1]);
-				smp->ts.origin.tv_nsec = SWAP_INT_TOH(*flags & RAW_BE_HDR, 32, i32[2]);
+				smp->sequence          = SWAP_INT_TOH(flags & RAW_BE_HDR, 32, i32[0]);
+				smp->ts.origin.tv_sec  = SWAP_INT_TOH(flags & RAW_BE_HDR, 32, i32[1]);
+				smp->ts.origin.tv_nsec = SWAP_INT_TOH(flags & RAW_BE_HDR, 32, i32[2]);
 				break;
 
 			case 64:
-				smp->sequence          = SWAP_INT_TOH(*flags & RAW_BE_HDR, 64, i64[0]);
-				smp->ts.origin.tv_sec  = SWAP_INT_TOH(*flags & RAW_BE_HDR, 64, i64[1]);
-				smp->ts.origin.tv_nsec = SWAP_INT_TOH(*flags & RAW_BE_HDR, 64, i64[2]);
+				smp->sequence          = SWAP_INT_TOH(flags & RAW_BE_HDR, 64, i64[0]);
+				smp->ts.origin.tv_sec  = SWAP_INT_TOH(flags & RAW_BE_HDR, 64, i64[1]);
+				smp->ts.origin.tv_nsec = SWAP_INT_TOH(flags & RAW_BE_HDR, 64, i64[2]);
 				break;
 		}
+
+		smp->has = SAMPLE_SEQUENCE | SAMPLE_ORIGIN;
 	}
 	else {
 		off = 0;
 
+		smp->has = 0;
 		smp->sequence = 0;
 		smp->ts.origin.tv_sec  = 0;
 		smp->ts.origin.tv_nsec = 0;
@@ -181,35 +183,32 @@ int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 		warn("Received more values than supported: length=%u, capacity=%u", smp->length, smp->capacity);
 		smp->length = smp->capacity;
 	}
-	
+
 	for (int i = 0; i < smp->length; i++) {
-		int fmt = *flags & RAW_FLT ? SAMPLE_DATA_FORMAT_FLOAT
+		int fmt = flags & RAW_FLT ? SAMPLE_DATA_FORMAT_FLOAT
 		                           : SAMPLE_DATA_FORMAT_INT;
-		
+
 		sample_set_data_format(smp, i, fmt);
-		
+
 		switch (fmt) {
 			case SAMPLE_DATA_FORMAT_FLOAT:
 				switch (bits) {
-					case 32: smp->data[i].f = SWAP_FLT_TOH(*flags & RAW_BE_FLT, f32[i+off]); break;
-					case 64: smp->data[i].f = SWAP_DBL_TOH(*flags & RAW_BE_FLT, f64[i+off]); break;
+					case 32: smp->data[i].f = SWAP_FLT_TOH(flags & RAW_BE_FLT, f32[i+off]); break;
+					case 64: smp->data[i].f = SWAP_DBL_TOH(flags & RAW_BE_FLT, f64[i+off]); break;
 				}
 				break;
-			
+
 			case SAMPLE_DATA_FORMAT_INT:
 				switch (bits) {
 					case 8:  smp->data[i].i = i8[i]; break;
-					case 16: smp->data[i].i = (int16_t) SWAP_INT_TOH(*flags & RAW_BE_INT, 16, i16[i+off]); break;
-					case 32: smp->data[i].i = (int32_t) SWAP_INT_TOH(*flags & RAW_BE_INT, 32, i32[i+off]); break;
-					case 64: smp->data[i].i = (int64_t) SWAP_INT_TOH(*flags & RAW_BE_INT, 64, i64[i+off]); break;
+					case 16: smp->data[i].i = (int16_t) SWAP_INT_TOH(flags & RAW_BE_INT, 16, i16[i+off]); break;
+					case 32: smp->data[i].i = (int32_t) SWAP_INT_TOH(flags & RAW_BE_INT, 32, i32[i+off]); break;
+					case 64: smp->data[i].i = (int64_t) SWAP_INT_TOH(flags & RAW_BE_INT, 64, i64[i+off]); break;
 				}
 				break;
 		}
 	}
 
-	smp->ts.received.tv_sec  = 0;
-	smp->ts.received.tv_nsec = 0;
-	
 	if (rbytes)
 		*rbytes = len;
 
diff --git a/lib/io/villas.c b/lib/io/villas.c
index 568dd339d..b2c614eec 100644
--- a/lib/io/villas.c
+++ b/lib/io/villas.c
@@ -33,18 +33,20 @@
 
 size_t villas_sprint_single(char *buf, size_t len, struct sample *s, int flags)
 {
-	size_t off = snprintf(buf, len, "%llu", (unsigned long long) s->ts.origin.tv_sec);
+	size_t off = 0;
 
-	if (flags & IO_FORMAT_NANOSECONDS)
+	if (flags & SAMPLE_ORIGIN) {
+		off += snprintf(buf + off, len - off, "%llu", (unsigned long long) s->ts.origin.tv_sec);
 		off += snprintf(buf + off, len - off, ".%09llu", (unsigned long long) s->ts.origin.tv_nsec);
+	}
 
-	if (flags & IO_FORMAT_OFFSET)
+	if (flags & SAMPLE_OFFSET)
 		off += snprintf(buf + off, len - off, "%+e", time_delta(&s->ts.origin, &s->ts.received));
 
-	if (flags & IO_FORMAT_SEQUENCE)
+	if (flags & SAMPLE_SEQUENCE)
 		off += snprintf(buf + off, len - off, "(%u)", s->sequence);
 
-	if (flags & IO_FORMAT_VALUES) {
+	if (flags & SAMPLE_VALUES) {
 		for (int i = 0; i < s->length; i++) {
 			switch ((s->format >> i) & 0x1) {
 				case SAMPLE_DATA_FORMAT_FLOAT:
@@ -62,14 +64,15 @@ size_t villas_sprint_single(char *buf, size_t len, struct sample *s, int flags)
 	return off;
 }
 
-size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *flags)
+size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int flags)
 {
 	char *end;
 	const char *ptr = buf;
 
-	int fl = 0;
 	double offset = 0;
 
+	s->has = 0;
+
 	/* Format: Seconds.NanoSeconds+Offset(SequenceNumber) Value1 Value2 ...
 	 * RegEx: (\d+(?:\.\d+)?)([-+]\d+(?:\.\d+)?(?:e[+-]?\d+)?)?(?:\((\d+)\))?
 	 *
@@ -81,14 +84,14 @@ size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *f
 	if (ptr == end || *end == '\n')
 		return -1;
 
+	s->has |= SAMPLE_ORIGIN;
+
 	/* Optional: nano seconds */
 	if (*end == '.') {
 		ptr = end + 1;
 
 		s->ts.origin.tv_nsec = (uint32_t) strtoul(ptr, &end, 10);
-		if (ptr != end)
-			fl |= IO_FORMAT_NANOSECONDS;
-		else
+		if (ptr == end)
 			return -3;
 	}
 	else
@@ -100,7 +103,7 @@ size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *f
 
 		offset = strtof(ptr, &end); /* offset is ignored for now */
 		if (ptr != end)
-			fl |= IO_FORMAT_OFFSET;
+			s->has |= SAMPLE_OFFSET;
 		else
 			return -4;
 	}
@@ -111,7 +114,7 @@ size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *f
 
 		s->sequence = strtoul(ptr, &end, 10);
 		if (ptr != end)
-			fl |= IO_FORMAT_SEQUENCE;
+			s->has |= SAMPLE_SEQUENCE;
 		else
 			return -5;
 
@@ -124,7 +127,7 @@ size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *f
 	     ptr  = end, s->length++) {
 		if (*end == '\n')
 			break;
-		
+
 		switch (s->format & (1 << s->length)) {
 			case SAMPLE_DATA_FORMAT_FLOAT:
 				s->data[s->length].f = strtod(ptr, &end);
@@ -138,22 +141,19 @@ size_t villas_sscan_single(const char *buf, size_t len, struct sample *s, int *f
 		if (end == ptr)
 			break;
 	}
-	
+
 	if (*end == '\n')
 		end++;
 
 	if (s->length > 0)
-		fl |= IO_FORMAT_VALUES;
+		s->has |= SAMPLE_VALUES;
 
-	if (flags)
-		*flags = fl;
-
-	if (fl & IO_FORMAT_OFFSET) {
+	if (s->has & SAMPLE_OFFSET) {
 		struct timespec off = time_from_double(offset);
 		s->ts.received = time_add(&s->ts.origin, &off);
+
+		s->has |= SAMPLE_RECEIVED;
 	}
-	else
-		s->ts.received = time_now();
 
 	return end - buf;
 }
@@ -165,28 +165,28 @@ int villas_sprint(char *buf, size_t len, size_t *wbytes, struct sample *smps[],
 
 	for (i = 0; i < cnt && off < len; i++)
 		off += villas_sprint_single(buf + off, len - off, smps[i], flags);
-	
+
 	if (wbytes)
 		*wbytes = off;
 
 	return i;
 }
 
-int villas_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int villas_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
 	int i;
 	size_t off = 0;
 
 	for (i = 0; i < cnt && off < len; i++)
 		off += villas_sscan_single(buf + off, len - off, smps[i], flags);
-	
+
 	if (rbytes)
 		*rbytes = off;
 
 	return i;
 }
 
-int villas_fscan_single(FILE *f, struct sample *s, int *flags)
+int villas_fscan_single(FILE *f, struct sample *s, int flags)
 {
 	char *ptr, line[4096];
 
@@ -209,7 +209,7 @@ int villas_fprint_single(FILE *f, struct sample *s, int flags)
 	ret = villas_sprint_single(line, sizeof(line), s, flags);
 	if (ret < 0)
 		return ret;
-	
+
 	fputs(line, f);
 
 	return 0;
@@ -228,7 +228,7 @@ int villas_fprint(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 	return i;
 }
 
-int villas_fscan(FILE *f, struct sample *smps[], unsigned cnt, int *flags)
+int villas_fscan(FILE *f, struct sample *smps[], unsigned cnt, int flags)
 {
 	int ret, i;
 
diff --git a/lib/io_format.c b/lib/io_format.c
index bbf3d1bd8..e857cfb9f 100644
--- a/lib/io_format.c
+++ b/lib/io_format.c
@@ -25,11 +25,10 @@
 
 #include "io_format.h"
 
-int io_format_sscan(struct io_format *fmt, char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int *flags)
+int io_format_sscan(struct io_format *fmt, char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsigned cnt, int flags)
 {
-	if (!flags)
-		flags = &fmt->flags;
-	
+	flags |= fmt->flags;
+
 	return fmt->sscan ? fmt->sscan(buf, len, rbytes, smps, cnt, flags) : -1;
 }
 
@@ -40,7 +39,7 @@ int io_format_sprint(struct io_format *fmt, char *buf, size_t len, size_t *wbyte
 	return fmt->sprint ? fmt->sprint(buf, len, wbytes, smps, cnt, flags) : -1;
 }
 
-int io_format_fscan(struct io_format *fmt, FILE *f, struct sample *smps[], unsigned cnt, int *flags)
+int io_format_fscan(struct io_format *fmt, FILE *f, struct sample *smps[], unsigned cnt, int flags)
 {
 	return fmt->sprint ? fmt->fscan(f, smps, cnt, flags) : -1;
 }
@@ -48,4 +47,4 @@ int io_format_fscan(struct io_format *fmt, FILE *f, struct sample *smps[], unsig
 int io_format_fprint(struct io_format *fmt, FILE *f, struct sample *smps[], unsigned cnt, int flags)
 {
 	return fmt->fprint ? fmt->fprint(f, smps, cnt, flags) : -1;
-}
\ No newline at end of file
+}
diff --git a/lib/node.c b/lib/node.c
index 2d6e92c7b..d5aa9945d 100644
--- a/lib/node.c
+++ b/lib/node.c
@@ -29,6 +29,7 @@
 #include "plugin.h"
 #include "config_helper.h"
 #include "mapping.h"
+#include "timing.h"
 
 int node_init(struct node *n, struct node_type *vt)
 {
@@ -278,9 +279,27 @@ int node_read(struct node *n, struct sample *smps[], unsigned cnt)
 		debug(LOG_NODES | 5, "Received %u samples from node %s", nread, node_name(n));
 	}
 
-	for (int i = 0; i < nread; i++)
+	/* Add missing fields */
+	for (int i = 0; i < nread; i++) {
 		smps[i]->source = n;
 
+		if (!(smps[i]->has & SAMPLE_SEQUENCE))
+			smps[i]->sequence = n->sequence++;
+
+		if (!(smps[i]->has & SAMPLE_ORIGIN) ||
+		    !(smps[i]->has & SAMPLE_RECEIVED)) {
+
+			struct timespec now = time_now();
+
+			if (!(smps[i]->has & SAMPLE_RECEIVED))
+				smps[i]->ts.received = now;
+
+			if (!(smps[i]->has & SAMPLE_ORIGIN))
+				smps[i]->ts.origin = now;
+		}
+	}
+
+	/* Run read hooks */
 	rread = hook_read_list(&n->hooks, smps, nread);
 	if (nread != rread) {
 		int skipped = nread - rread;
diff --git a/lib/nodes/file.c b/lib/nodes/file.c
index 6ecef27f7..8fef1736e 100644
--- a/lib/nodes/file.c
+++ b/lib/nodes/file.c
@@ -104,7 +104,7 @@ int file_parse(struct node *n, json_t *cfg)
 
 	f->epoch = time_from_double(epoch_flt);
 	f->uri_tmpl = uri_tmpl ? strdup(uri_tmpl) : NULL;
-	
+
 	f->format = io_format_lookup(format);
 	if (!f->format)
 		error("Invalid format '%s' for node %s", format, node_name(n));
@@ -205,7 +205,7 @@ int file_start(struct node *n)
 	f->uri = file_format_name(f->uri_tmpl, &now);
 
 	/* Open file */
-	flags = IO_FORMAT_ALL;
+	flags = SAMPLE_ALL;
 	if (f->flush)
 		flags |= IO_FLUSH;
 
@@ -342,7 +342,7 @@ int file_write(struct node *n, struct sample *smps[], unsigned cnt)
 int file_fd(struct node *n)
 {
 	struct file *f = n->_vd;
-	
+
 	if (f->rate)
 		return task_fd(&f->task);
 	else {
diff --git a/lib/nodes/nanomsg.c b/lib/nodes/nanomsg.c
index 3bf0e4b5c..af5372fb9 100644
--- a/lib/nodes/nanomsg.c
+++ b/lib/nodes/nanomsg.c
@@ -111,7 +111,7 @@ int nanomsg_parse(struct node *n, json_t *cfg)
 		if (ret < 0)
 			error("Invalid type for 'subscribe' setting of node %s", node_name(n));
 	}
-	
+
 	m->format = io_format_lookup(format);
 	if (!m->format)
 		error("Invalid format '%s' for node %s", format, node_name(n));
@@ -223,7 +223,7 @@ int nanomsg_read(struct node *n, struct sample *smps[], unsigned cnt)
 	if (bytes < 0)
 		return -1;
 
-	return io_format_sscan(m->format, data, bytes, NULL, smps, cnt, NULL);
+	return io_format_sscan(m->format, data, bytes, NULL, smps, cnt, 0);
 }
 
 int nanomsg_write(struct node *n, struct sample *smps[], unsigned cnt)
@@ -235,7 +235,7 @@ int nanomsg_write(struct node *n, struct sample *smps[], unsigned cnt)
 
 	char data[NANOMSG_MAX_PACKET_LEN];
 
-	ret = io_format_sprint(m->format, data, sizeof(data), &wbytes, smps, cnt, IO_FORMAT_ALL);
+	ret = io_format_sprint(m->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_ALL);
 	if (ret <= 0)
 		return -1;
 
@@ -250,14 +250,14 @@ int nanomsg_fd(struct node *n)
 {
 	int ret;
 	struct nanomsg *m = n->_vd;
-	
+
 	int fd;
 	size_t len = sizeof(fd);
 
 	ret = nn_getsockopt(m->subscriber.socket, NN_SOL_SOCKET, NN_RCVFD, &fd, &len);
 	if (ret)
 		return ret;
-	
+
 	return fd;
 }
 
diff --git a/lib/nodes/shmem.c b/lib/nodes/shmem.c
index 85ed995e2..7e532bd55 100644
--- a/lib/nodes/shmem.c
+++ b/lib/nodes/shmem.c
@@ -128,11 +128,6 @@ int shmem_read(struct node *n, struct sample *smps[], unsigned cnt)
 	sample_copy_many(smps, shared_smps, recv);
 	sample_put_many(shared_smps, recv);
 
-	struct timespec ts_recv = time_now();
-
-	for (int i = 0; i < recv; i++)
-		smps[i]->ts.received = ts_recv;
-
 	return recv;
 }
 
@@ -140,25 +135,18 @@ int shmem_write(struct node *n, struct sample *smps[], unsigned cnt)
 {
 	struct shmem *shm = n->_vd;
 	struct sample *shared_smps[cnt]; /* Samples need to be copied to the shared pool first */
-	int avail, pushed, len;
+	int avail, pushed;
 
 	avail = sample_alloc(&shm->intf.write.shared->pool, shared_smps, cnt);
 	if (avail != cnt)
 		warn("Pool underrun for shmem node %s", shm->out_name);
 
 	for (int i = 0; i < avail; i++) {
+		sample_copy(shared_smps[i], smps[i]);
+
 		/* Since the node isn't in shared memory, the source can't be accessed */
 		shared_smps[i]->source = NULL;
-		shared_smps[i]->sequence = smps[i]->sequence;
-		shared_smps[i]->ts = smps[i]->ts;
-
-		len = MIN(smps[i]->length, shared_smps[i]->capacity);
-		if (len != smps[i]->length)
-			warn("Losing data because of sample capacity mismatch in node %s", node_name(n));
-
-		memcpy(shared_smps[i]->data, smps[i]->data, SAMPLE_DATA_LEN(len));
-
-		shared_smps[i]->length = len;
+		shared_smps[i]->has &= ~SAMPLE_SOURCE;
 	}
 
 	pushed = shmem_int_write(&shm->intf, shared_smps, avail);
diff --git a/lib/nodes/signal.c b/lib/nodes/signal.c
index bae4cbe09..397dd0f33 100644
--- a/lib/nodes/signal.c
+++ b/lib/nodes/signal.c
@@ -210,7 +210,7 @@ int signal_read(struct node *n, struct sample *smps[], unsigned cnt)
 	struct signal *s = n->_vd;
 	struct sample *t = smps[0];
 
-	struct timespec ts_recv;
+	struct timespec ts;
 	int steps;
 
 	assert(cnt == 1);
@@ -222,20 +222,20 @@ int signal_read(struct node *n, struct sample *smps[], unsigned cnt)
 		if (steps > 1)
 			warn("Missed steps: %u", steps);
 
-		ts_recv = time_now();
+		ts = time_now();
 	}
 	else {
 		struct timespec offset = time_from_double(s->counter * 1.0 / s->rate);
 
-		ts_recv = time_add(&s->started, &offset);
+		ts = time_add(&s->started, &offset);
 
 		steps = 1;
 	}
 
-	double running = time_delta(&s->started, &ts_recv);
+	double running = time_delta(&s->started, &ts);
 
-	t->ts.origin =
-	t->ts.received = ts_recv;
+	t->has = SAMPLE_ORIGIN | SAMPLE_VALUES | SAMPLE_SEQUENCE;
+	t->ts.origin = ts;
 	t->sequence = s->counter;
 	t->length = n->samplelen;
 
diff --git a/lib/nodes/socket.c b/lib/nodes/socket.c
index c5b2aa8cb..7415328ac 100644
--- a/lib/nodes/socket.c
+++ b/lib/nodes/socket.c
@@ -344,7 +344,7 @@ int socket_read(struct node *n, struct sample *smps[], unsigned cnt)
 		return 0;
 	}
 
-	ret = io_format_sscan(s->format, bufptr, bytes, &rbytes, smps, cnt, NULL);
+	ret = io_format_sscan(s->format, bufptr, bytes, &rbytes, smps, cnt, 0);
 
 	if (bytes != rbytes)
 		warn("Received invalid packet from node: %s bytes=%zu, rbytes=%zu", node_name(n), bytes, rbytes);
@@ -361,7 +361,7 @@ int socket_write(struct node *n, struct sample *smps[], unsigned cnt)
 	ssize_t bytes;
 	size_t wbytes;
 
-	ret = io_format_sprint(s->format, data, sizeof(data), &wbytes, smps, cnt, IO_FORMAT_ALL);
+	ret = io_format_sprint(s->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_ALL);
 	if (ret < 0)
 		return -1;
 
diff --git a/lib/nodes/websocket.c b/lib/nodes/websocket.c
index 52ebb1e72..a89e7b8e0 100644
--- a/lib/nodes/websocket.c
+++ b/lib/nodes/websocket.c
@@ -47,9 +47,9 @@ static char * websocket_connection_name(struct websocket_connection *c)
 		if (c->wsi) {
 			char name[128];
 			char ip[128];
-			
+
 			lws_get_peer_addresses(c->wsi, lws_get_socket_fd(c->wsi), name, sizeof(name), ip, sizeof(ip));
-			
+
 			strcatf(&c->_name, "remote.ip=%s, remote.name=%s", ip, name);
 		}
 		else if (c->destination)
@@ -75,15 +75,15 @@ static void websocket_destination_destroy(struct websocket_destination *d)
 static int websocket_connection_write(struct websocket_connection *c, struct sample *smps[], unsigned cnt)
 {
 	int pushed;
-	
+
 	pushed = queue_push_many(&c->queue, (void **) smps, cnt);
 	if (pushed < cnt)
 		warn("Queue overrun in WebSocket connection: %s", websocket_connection_name(c));
-	
+
 	sample_get_many(smps, cnt);
-	
+
 	debug(LOG_WEBSOCKET | 10, "Enqueued %u samples to %s", pushed, websocket_connection_name(c));
-	
+
 	/* Client connections which are currently conecting don't have an associate c->wsi yet */
 	if (c->wsi)
 		lws_callback_on_writable(c->wsi);
@@ -102,17 +102,17 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 {
 	int ret, recvd, pulled, cnt = 128;
 	struct websocket_connection *c = user;
-	
+
 	switch (reason) {
 		case LWS_CALLBACK_CLIENT_ESTABLISHED:
 			c->wsi = wsi;
 			c->state = STATE_ESTABLISHED;
-			
+
 			buffer_init(&c->buffers.recv, 1 << 12);
 			buffer_init(&c->buffers.send, 1 << 12);
 
 			debug(LOG_WEBSOCKET | 10, "Established WebSocket connection: %s", websocket_connection_name(c));
-			
+
 			/* Schedule writable callback in case we have something to send */
 			if (queue_available(&c->queue) > 0)
 				lws_callback_on_writable(wsi);
@@ -146,7 +146,7 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 				websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_PROTOCOL_ERR, "Invalid URL");
 				return -1;
 			}
-			
+
 			node = strtok(uri, "/.");
 			if (strlen(node) == 0)
 				c->node = NULL;
@@ -160,7 +160,7 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 					return -1;
 				}
 			}
-			
+
 			if (!format)
 				format = "webmsg";
 
@@ -169,16 +169,16 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 				websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_PROTOCOL_ERR, "Invalid format");
 				return -1;
 			}
-			
+
 			buffer_init(&c->buffers.recv, 1 << 12);
 			buffer_init(&c->buffers.send, 1 << 12);
-			
+
 			ret = queue_init(&c->queue, DEFAULT_QUEUELEN, &memtype_hugepage);
 			if (ret)
 				return -1;
 
 			list_push(&connections, c);
-			
+
 			debug(LOG_WEBSOCKET | 10, "Established WebSocket connection: %s", websocket_connection_name(c));
 
 			break;
@@ -189,10 +189,10 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 			warn("Failed to establish WebSocket connection: %s, reason=%s", websocket_connection_name(c), in ? (char *) in : "unkown");
 
 			return -1;
-		
+
 		case LWS_CALLBACK_CLOSED:
 			debug(LOG_WEBSOCKET | 10, "Closed WebSocket connection: %s", websocket_connection_name(c));
-			
+
 			if (c->state != STATE_SHUTDOWN) {
 				/** @todo Attempt reconnect here */
 			}
@@ -219,7 +219,7 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 		case LWS_CALLBACK_CLIENT_WRITEABLE:
 		case LWS_CALLBACK_SERVER_WRITEABLE: {
 			size_t wbytes;
-			
+
 			if (c->state == STATE_SHUTDOWN) {
 				websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_GOINGAWAY, "Node stopped");
 				return -1;
@@ -229,51 +229,51 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 
 			pulled = queue_pull_many(&c->queue, (void **) smps, cnt);
 			if (pulled > 0) {
-				io_format_sprint(c->format, c->buffers.send.buf + LWS_PRE, c->buffers.send.size - LWS_PRE, &wbytes, smps, pulled, IO_FORMAT_ALL);
-				
+				io_format_sprint(c->format, c->buffers.send.buf + LWS_PRE, c->buffers.send.size - LWS_PRE, &wbytes, smps, pulled, SAMPLE_ALL);
+
 				ret = lws_write(wsi, (unsigned char *) c->buffers.send.buf + LWS_PRE, wbytes, c->format->flags & IO_FORMAT_BINARY ? LWS_WRITE_BINARY : LWS_WRITE_TEXT);
 
 				sample_put_many(smps, pulled);
 
 				debug(LOG_WEBSOCKET | 10, "Send %d samples to connection: %s, bytes=%d", pulled, websocket_connection_name(c), ret);
 			}
-			
+
 			if (queue_available(&c->queue) > 0)
 				lws_callback_on_writable(wsi);
-			
+
 			break;
 		}
 
 		case LWS_CALLBACK_CLIENT_RECEIVE:
-		case LWS_CALLBACK_RECEIVE:		
+		case LWS_CALLBACK_RECEIVE:
 			if (!c->node) {
 				websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_PROTOCOL_ERR, "Catch-all connection can not receive.");
 				return -1;
 			}
-			
+
 			if (lws_is_first_fragment(wsi))
 				buffer_clear(&c->buffers.recv);
-			
+
 			ret = buffer_append(&c->buffers.recv, in, len);
 			if (ret) {
 				websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_UNACCEPTABLE_OPCODE, "Failed to process data");
 				return -1;
 			}
-			
+
 			/* We dont try to parse the frame yet, as we have to wait for the remaining fragments */
 			if (lws_is_final_fragment(wsi)) {
 				struct timespec ts_recv = time_now();
 
 				struct websocket *w = c->node->_vd;
 				struct sample **smps = alloca(cnt * sizeof(struct sample *));
-	
+
 				ret = sample_alloc(&w->pool, smps, cnt);
 				if (ret != cnt) {
 					warn("Pool underrun for connection: %s", websocket_connection_name(c));
 					break;
 				}
 
-				recvd = io_format_sscan(c->format, c->buffers.recv.buf, c->buffers.recv.len, NULL, smps, cnt, NULL);
+				recvd = io_format_sscan(c->format, c->buffers.recv.buf, c->buffers.recv.len, NULL, smps, cnt, 0);
 				if (recvd < 0) {
 					warn("Failed to parse sample data received on connection: %s", websocket_connection_name(c));
 					break;
@@ -282,13 +282,15 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 				debug(LOG_WEBSOCKET | 10, "Received %d samples to connection: %s", recvd, websocket_connection_name(c));
 
 				/* Set receive timestamp */
-				for (int i = 0; i < recvd; i++)
+				for (int i = 0; i < recvd; i++) {
 					smps[i]->ts.received = ts_recv;
+					smps[i]->has |= SAMPLE_RECEIVED;
+				}
 
 				ret = queue_signalled_push_many(&w->queue, (void **) smps, recvd);
 				if (ret != recvd)
 					warn("Queue overrun for connection: %s", websocket_connection_name(c));
-			
+
 				if (c->state == STATE_SHUTDOWN) {
 					websocket_connection_close(c, wsi, LWS_CLOSE_STATUS_GOINGAWAY, "Node stopped");
 					return -1;
@@ -300,7 +302,7 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 		default:
 			break;
 	}
-	
+
 	return 0;
 }
 
@@ -365,7 +367,7 @@ int websocket_start(struct node *n)
 		d->info.context = web->context;
 		d->info.vhost = web->vhost;
 		d->info.userdata = c;
-		
+
 		ret = queue_init(&c->queue, DEFAULT_QUEUELEN, &memtype_hugepage);
 		if (ret)
 			return -1;
@@ -382,29 +384,29 @@ int websocket_stop(struct node *n)
 {
 	int ret;
 	struct websocket *w = n->_vd;
-	
+
 	/* Wait for all connections to be closed */
 	for (;;) {
 		int connecting = 0;
-		
+
 		for (int i = 0; i < list_length(&w->destinations); i++) {
 			struct websocket_destination *d = list_at(&w->destinations, i);
 			struct websocket_connection *c = d->info.userdata;
-		
+
 			if (c->state == STATE_CONNECTING)
 				connecting++;
 		}
-		
+
 		if (connecting == 0)
 			break;
-		
+
 		debug(LOG_WEBSOCKET | 10, "Waiting for %d client connections to be established", connecting);
 		sleep(1);
 	}
-	
+
 	for (size_t i = 0; i < list_length(&connections); i++) {
 		struct websocket_connection *c = list_at(&connections, i);
-		
+
 		if (c->node != n)
 			continue;
 
@@ -474,7 +476,7 @@ int websocket_write(struct node *n, struct sample *smps[], unsigned cnt)
 
 	for (size_t i = 0; i < list_length(&connections); i++) {
 		struct websocket_connection *c = list_at(&connections, i);
-		
+
 		if (c->node == n || c->node == NULL)
 			websocket_connection_write(c, cpys, cnt);
 	}
@@ -561,7 +563,7 @@ char * websocket_print(struct node *n)
 int websocket_fd(struct node *n)
 {
 	struct websocket *w = n->_vd;
-	
+
 	return queue_signalled_fd(&w->queue);
 }
 
diff --git a/lib/nodes/zeromq.c b/lib/nodes/zeromq.c
index 66819249e..720d8c3cd 100644
--- a/lib/nodes/zeromq.c
+++ b/lib/nodes/zeromq.c
@@ -125,7 +125,7 @@ int zeromq_parse(struct node *n, json_t *cfg)
 
 	z->subscriber.endpoint = ep ? strdup(ep) : NULL;
 	z->filter = filter ? strdup(filter) : NULL;
-	
+
 	z->format = io_format_lookup(format);
 	if (!z->format)
 		error("Invalid format '%s' for node %s", format, node_name(n));
@@ -429,7 +429,7 @@ int zeromq_read(struct node *n, struct sample *smps[], unsigned cnt)
 	if (ret < 0)
 		return ret;
 
-	recv = io_format_sscan(z->format, zmq_msg_data(&m), zmq_msg_size(&m), NULL, smps, cnt, NULL);
+	recv = io_format_sscan(z->format, zmq_msg_data(&m), zmq_msg_size(&m), NULL, smps, cnt, 0);
 
 	ret = zmq_msg_close(&m);
 	if (ret)
@@ -448,7 +448,7 @@ int zeromq_write(struct node *n, struct sample *smps[], unsigned cnt)
 
 	char data[4096];
 
-	ret = io_format_sprint(z->format, data, sizeof(data), &wbytes, smps, cnt, IO_FORMAT_ALL);
+	ret = io_format_sprint(z->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_ALL);
 	if (ret <= 0)
 		return -1;
 
@@ -492,10 +492,10 @@ int zeromq_fd(struct node *n)
 {
 	int ret;
 	struct zeromq *z = n->_vd;
-	
+
 	int fd;
 	size_t len = sizeof(fd);
-	
+
 	ret = zmq_getsockopt(z->subscriber.socket, ZMQ_FD, &fd, &len);
 	if (ret)
 		return ret;
diff --git a/lib/sample.c b/lib/sample.c
index ad5b86101..eda960c2b 100644
--- a/lib/sample.c
+++ b/lib/sample.c
@@ -93,10 +93,9 @@ int sample_copy(struct sample *dst, struct sample *src)
 	dst->sequence = src->sequence;
 	dst->format = src->format;
 	dst->source = src->source;
+	dst->has = src->has;
 
-	dst->ts.origin   = src->ts.origin;
-	dst->ts.received = src->ts.received;
-	dst->ts.sent     = src->ts.sent;
+	dst->ts = src->ts;
 
 	memcpy(&dst->data, &src->data, SAMPLE_DATA_LEN(dst->length));
 
diff --git a/src/hook.c b/src/hook.c
index f82aa4439..a0dcd652e 100644
--- a/src/hook.c
+++ b/src/hook.c
@@ -180,7 +180,7 @@ check:		if (optarg == endptr)
 	if (!p)
 		error("Unknown IO format '%s'", format);
 
-	ret = io_init(&io, &p->io, IO_FORMAT_ALL);
+	ret = io_init(&io, &p->io, SAMPLE_ALL);
 	if (ret)
 		error("Failed to initialize IO");
 
diff --git a/src/pipe.c b/src/pipe.c
index 33bca57f5..2b0cb258b 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -292,7 +292,7 @@ check:		if (optarg == endptr)
 	if (!p)
 		error("Invalid format: %s", format);
 
-	ret = io_init(&io, &p->io, IO_FORMAT_ALL);
+	ret = io_init(&io, &p->io, SAMPLE_ALL);
 	if (ret)
 		error("Failed to initialize IO");
 
diff --git a/src/signal.c b/src/signal.c
index 77c6e9864..2543b8759 100644
--- a/src/signal.c
+++ b/src/signal.c
@@ -136,7 +136,7 @@ int main(int argc, char *argv[])
 	if (!p)
 		error("Invalid output format '%s'", format);
 
-	ret = io_init(&io, &p->io, IO_FLUSH | (IO_FORMAT_ALL & ~IO_FORMAT_OFFSET));
+	ret = io_init(&io, &p->io, IO_FLUSH | (SAMPLE_ALL & ~SAMPLE_OFFSET));
 	if (ret)
 		error("Failed to initialize output");
 
diff --git a/src/test-cmp.c b/src/test-cmp.c
index 7b21f3045..245fd9e32 100644
--- a/src/test-cmp.c
+++ b/src/test-cmp.c
@@ -65,7 +65,7 @@ void usage()
 int main(int argc, char *argv[])
 {
 	int ret;
-	
+
 	/* Default values */
 	double epsilon = 1e-9;
 	int timestamp = 1;
@@ -77,7 +77,6 @@ int main(int argc, char *argv[])
 	struct sample *samples[2];
 
 	struct {
-		int flags;
 		char *path;
 		FILE *handle;
 		struct sample *sample;
@@ -150,11 +149,11 @@ check:		if (optarg == endptr)
 		serror("Failed to open file: %s", f2.path);
 
 	while (!feof(f1.handle) && !feof(f2.handle)) {
-		ret = villas_fscan(f1.handle, &f1.sample, 1, &f1.flags);
+		ret = villas_fscan(f1.handle, &f1.sample, 1, 0);
 		if (ret < 0 && !feof(f1.handle))
 			goto out;
 
-		ret = villas_fscan(f2.handle, &f2.sample, 1, &f2.flags);
+		ret = villas_fscan(f2.handle, &f2.sample, 1, 0);
 		if (ret < 0 && !feof(f2.handle))
 			goto out;
 
@@ -168,7 +167,7 @@ check:		if (optarg == endptr)
 		}
 
 		/* Compare sequence no */
-		if (sequence && (f1.flags & IO_FORMAT_SEQUENCE) && (f2.flags & IO_FORMAT_SEQUENCE)) {
+		if (sequence && (f1.sample->has & SAMPLE_SEQUENCE) && (f2.sample->has & SAMPLE_SEQUENCE)) {
 			if (f1.sample->sequence != f2.sample->sequence) {
 				printf("sequence no: %d != %d\n", f1.sample->sequence, f2.sample->sequence);
 				ret = 2;