diff --git a/include/villas/node.h b/include/villas/node.h
index 94e0235de..07c44694e 100644
--- a/include/villas/node.h
+++ b/include/villas/node.h
@@ -69,6 +69,8 @@ struct node
 
 int node_init(struct node *n, struct node_type *vt);
 
+int node_init2(struct node *n);
+
 /** Parse settings of a node.
  *
  * @param cfg A JSON object containing the configuration of the node.
diff --git a/include/villas/node_type.h b/include/villas/node_type.h
index 09330eb4a..5b3948bab 100644
--- a/include/villas/node_type.h
+++ b/include/villas/node_type.h
@@ -146,7 +146,7 @@ struct node_type {
 	 * @param n	A pointer to the node object.
 	 */
 	int (*reverse)(struct node *n);
-	
+
 	/** Return a file descriptor which can be used by poll / select to detect the availability of new data. */
 	int (*fd)(struct node *n);
 };
diff --git a/include/villas/sample.h b/include/villas/sample.h
index ef2cefb4f..124220860 100644
--- a/include/villas/sample.h
+++ b/include/villas/sample.h
@@ -53,28 +53,35 @@ enum sample_data_format {
 };
 
 /** 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. */
+enum sample_flags {
+	SAMPLE_HAS_ORIGIN	= (1 << 0), /**< Include origin timestamp in output. */
+	SAMPLE_HAS_RECEIVED	= (1 << 1), /**< Include receive timestamp in output. */
+	SAMPLE_HAS_OFFSET	= (1 << 2), /**< Include offset (received - origin timestamp) in output. */
+	SAMPLE_HAS_SOURCE	= (1 << 3), /**< This sample has a valid sample::source field. */
+	SAMPLE_HAS_ID		= (1 << 4), /**< This sample has a valid sample::id field. */
+	SAMPLE_HAS_SEQUENCE	= (1 << 5), /**< Include sequence number in output. */
+	SAMPLE_HAS_VALUES	= (1 << 6), /**< Include values in output. */
+	SAMPLE_HAS_FORMAT	= (1 << 7), /**< This sample has a valid sample::format field. */
+	SAMPLE_HAS_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 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 flags;		/**< Flags are used to store binary properties of a sample. */
 
-	int id;
+	int id;			/**< The id field is usually the same as sample::source::id */
+	struct node *source;	/**< The node from which this sample originates. */
 
-	atomic_int refcnt;   /**< Reference counter. */
-	off_t pool_off;	     /**< This sample belongs to this memory pool (relative pointer). */
-	struct node *source; /**< The node from which this sample originates. */
+	atomic_int refcnt;	/**< Reference counter. */
+	off_t pool_off;		/**< This sample belongs to this memory pool (relative pointer). See sample_pool(). */
+
+	/** A long bitfield indicating the number representation of the first 64 values in sample::data[].
+	 *
+	 * @see sample_data_format
+	 */
+	uint64_t format;
 
 	/** All timestamps are seconds / nano seconds after 1.1.1970 UTC */
 	struct {
@@ -83,14 +90,6 @@ 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
-	 */
-	uint64_t format;
-
 	/** The values. */
 	union {
 		double  f;	/**< Floating point values. */
@@ -98,6 +97,7 @@ struct sample {
 	} data[];		/**< Data is in host endianess! */
 };
 
+/** Get the address of the pool to which the sample belongs. */
 #define sample_pool(s) ((struct pool *) ((char *) (s) + (s)->pool_off))
 
 /** Request \p cnt samples from memory pool \p p and initialize them.
diff --git a/lib/hooks/print.c b/lib/hooks/print.c
index 2d1d92cfe..29b9dce2b 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, SAMPLE_ALL);
+	ret = io_init(&p->io, p->format, SAMPLE_HAS_ALL);
 	if (ret)
 		return ret;
 
diff --git a/lib/io/csv.c b/lib/io/csv.c
index a55332b3c..d573ff9c8 100644
--- a/lib/io/csv.c
+++ b/lib/io/csv.c
@@ -32,10 +32,10 @@ size_t csv_sprint_single(char *buf, size_t len, struct sample *s, int flags)
 {
 	size_t off = 0;
 
-	if (flags & SAMPLE_ORIGIN)
+	if (flags & SAMPLE_HAS_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)
+	if (flags & SAMPLE_HAS_SEQUENCE)
 		off += snprintf(buf + off, len - off, "%c%u", CSV_SEPARATOR, s->sequence);
 
 	for (int i = 0; i < s->length; i++) {
@@ -59,7 +59,7 @@ 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->flags = 0;
 
 	s->ts.origin.tv_sec = strtoul(ptr, &end, 10);
 	if (end == ptr || *end == '\n')
@@ -73,13 +73,13 @@ size_t csv_sscan_single(const char *buf, size_t len, struct sample *s, int flags
 
 	ptr = end;
 
-	s->has |= SAMPLE_ORIGIN;
+	s->flags |= SAMPLE_HAS_ORIGIN;
 
 	s->sequence = strtoul(ptr, &end, 10);
 	if (end == ptr || *end == '\n')
 		goto out;
 
-	s->has |= SAMPLE_SEQUENCE;
+	s->flags |= SAMPLE_HAS_SEQUENCE;
 
 	for (ptr  = end, s->length = 0;
 	                 s->length < s->capacity;
@@ -105,7 +105,7 @@ out:	if (*end == '\n')
 		end++;
 
 	if (s->length > 0)
-		s->has |= SAMPLE_VALUES;
+		s->flags |= SAMPLE_HAS_VALUES;
 
 	return end - buf;
 }
diff --git a/lib/io/json.c b/lib/io/json.c
index bf21abebb..769089d0e 100644
--- a/lib/io/json.c
+++ b/lib/io/json.c
@@ -34,13 +34,13 @@ int json_pack_sample(json_t **j, struct sample *smp, int flags)
 			"received", smp->ts.received.tv_sec, smp->ts.received.tv_nsec,
 			"sent",     smp->ts.sent.tv_sec,     smp->ts.sent.tv_nsec);
 
-	if (flags & SAMPLE_SEQUENCE) {
+	if (flags & SAMPLE_HAS_SEQUENCE) {
 		json_t *json_sequence = json_integer(smp->sequence);
 
 		json_object_set(json_smp, "sequence", json_sequence);
 	}
 
-	if (flags & SAMPLE_VALUES) {
+	if (flags & SAMPLE_HAS_VALUES) {
 		json_t *json_data = json_array();
 
 		for (int i = 0; i < smp->length; i++) {
@@ -99,7 +99,7 @@ int json_unpack_sample(json_t *json_smp, struct sample *smp, int flags)
 	if (!json_is_array(json_data))
 		return -1;
 
-	smp->has = SAMPLE_ORIGIN | SAMPLE_RECEIVED | SAMPLE_SEQUENCE;
+	smp->flags = SAMPLE_HAS_ORIGIN | SAMPLE_HAS_RECEIVED | SAMPLE_HAS_SEQUENCE;
 	smp->length = 0;
 
 	json_array_foreach(json_data, i, json_value) {
@@ -125,7 +125,7 @@ int json_unpack_sample(json_t *json_smp, struct sample *smp, int flags)
 	}
 
 	if (smp->length > 0)
-		smp->has |= SAMPLE_VALUES;
+		smp->flags |= SAMPLE_HAS_VALUES;
 
 	return 0;
 }
diff --git a/lib/io/msg.c b/lib/io/msg.c
index 286d7a77b..ee20593b6 100644
--- a/lib/io/msg.c
+++ b/lib/io/msg.c
@@ -79,7 +79,7 @@ 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->flags = SAMPLE_HAS_ORIGIN | SAMPLE_HAS_SEQUENCE | SAMPLE_HAS_VALUES | SAMPLE_HAS_ID;
 	smp->length = MIN(msg->length, smp->capacity);
 	smp->sequence = msg->sequence;
 	smp->id = msg->id;
diff --git a/lib/io/raw.c b/lib/io/raw.c
index 6a79ddc17..c7c313984 100644
--- a/lib/io/raw.c
+++ b/lib/io/raw.c
@@ -169,12 +169,12 @@ int raw_sscan(char *buf, size_t len, size_t *rbytes, struct sample *smps[], unsi
 				break;
 		}
 
-		smp->has = SAMPLE_SEQUENCE | SAMPLE_ORIGIN;
+		smp->flags = SAMPLE_HAS_SEQUENCE | SAMPLE_HAS_ORIGIN;
 	}
 	else {
 		off = 0;
 
-		smp->has = 0;
+		smp->flags = 0;
 		smp->sequence = 0;
 		smp->ts.origin.tv_sec  = 0;
 		smp->ts.origin.tv_nsec = 0;
diff --git a/lib/io/villas_human.c b/lib/io/villas_human.c
index aa179fac9..f9b2f65f4 100644
--- a/lib/io/villas_human.c
+++ b/lib/io/villas_human.c
@@ -40,18 +40,18 @@ size_t villas_human_sprint_single(char *buf, size_t len, struct sample *s, int f
 {
 	size_t off = 0;
 
-	if (flags & SAMPLE_ORIGIN) {
+	if (flags & SAMPLE_HAS_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 & SAMPLE_RECEIVED)
+	if (flags & SAMPLE_HAS_RECEIVED)
 		off += snprintf(buf + off, len - off, "%+e", time_delta(&s->ts.origin, &s->ts.received));
 
-	if (flags & SAMPLE_SEQUENCE)
+	if (flags & SAMPLE_HAS_SEQUENCE)
 		off += snprintf(buf + off, len - off, "(%u)", s->sequence);
 
-	if (flags & SAMPLE_VALUES) {
+	if (flags & SAMPLE_HAS_VALUES) {
 		for (int i = 0; i < s->length; i++) {
 			switch (sample_get_data_format(s, i)) {
 				case SAMPLE_DATA_FORMAT_FLOAT:
@@ -76,7 +76,7 @@ size_t villas_human_sscan_single(const char *buf, size_t len, struct sample *s,
 
 	double offset = 0;
 
-	s->has = 0;
+	s->flags = 0;
 
 	/* Format: Seconds.NanoSeconds+Offset(SequenceNumber) Value1 Value2 ...
 	 * RegEx: (\d+(?:\.\d+)?)([-+]\d+(?:\.\d+)?(?:e[+-]?\d+)?)?(?:\((\d+)\))?
@@ -89,7 +89,7 @@ size_t villas_human_sscan_single(const char *buf, size_t len, struct sample *s,
 	if (ptr == end || *end == '\n')
 		return -1;
 
-	s->has |= SAMPLE_ORIGIN;
+	s->flags |= SAMPLE_HAS_ORIGIN;
 
 	/* Optional: nano seconds */
 	if (*end == '.') {
@@ -108,7 +108,7 @@ size_t villas_human_sscan_single(const char *buf, size_t len, struct sample *s,
 
 		offset = strtof(ptr, &end); /* offset is ignored for now */
 		if (ptr != end)
-			s->has |= SAMPLE_OFFSET;
+			s->flags |= SAMPLE_HAS_OFFSET;
 		else
 			return -4;
 	}
@@ -119,7 +119,7 @@ size_t villas_human_sscan_single(const char *buf, size_t len, struct sample *s,
 
 		s->sequence = strtoul(ptr, &end, 10);
 		if (ptr != end)
-			s->has |= SAMPLE_SEQUENCE;
+			s->flags |= SAMPLE_HAS_SEQUENCE;
 		else
 			return -5;
 
@@ -151,13 +151,13 @@ size_t villas_human_sscan_single(const char *buf, size_t len, struct sample *s,
 		end++;
 
 	if (s->length > 0)
-		s->has |= SAMPLE_VALUES;
+		s->flags |= SAMPLE_HAS_VALUES;
 
-	if (s->has & SAMPLE_OFFSET) {
+	if (s->flags & SAMPLE_HAS_OFFSET) {
 		struct timespec off = time_from_double(offset);
 		s->ts.received = time_add(&s->ts.origin, &off);
 
-		s->has |= SAMPLE_RECEIVED;
+		s->flags |= SAMPLE_HAS_RECEIVED;
 	}
 
 	return end - buf;
diff --git a/lib/node.c b/lib/node.c
index d5aa9945d..f02866970 100644
--- a/lib/node.c
+++ b/lib/node.c
@@ -283,18 +283,18 @@ int node_read(struct node *n, struct sample *smps[], unsigned cnt)
 	for (int i = 0; i < nread; i++) {
 		smps[i]->source = n;
 
-		if (!(smps[i]->has & SAMPLE_SEQUENCE))
+		if (!(smps[i]->flags & SAMPLE_HAS_SEQUENCE))
 			smps[i]->sequence = n->sequence++;
 
-		if (!(smps[i]->has & SAMPLE_ORIGIN) ||
-		    !(smps[i]->has & SAMPLE_RECEIVED)) {
+		if (!(smps[i]->flags & SAMPLE_HAS_ORIGIN) ||
+		    !(smps[i]->flags & SAMPLE_HAS_RECEIVED)) {
 
 			struct timespec now = time_now();
 
-			if (!(smps[i]->has & SAMPLE_RECEIVED))
+			if (!(smps[i]->flags & SAMPLE_HAS_RECEIVED))
 				smps[i]->ts.received = now;
 
-			if (!(smps[i]->has & SAMPLE_ORIGIN))
+			if (!(smps[i]->flags & SAMPLE_HAS_ORIGIN))
 				smps[i]->ts.origin = now;
 		}
 	}
@@ -320,6 +320,7 @@ int node_write(struct node *n, struct sample *smps[], unsigned cnt)
 	if (!n->_vt->write)
 		return -1;
 
+	/* Run write hooks */
 	cnt = hook_write_list(&n->hooks, smps, cnt);
 	if (cnt <= 0)
 		return cnt;
diff --git a/lib/nodes/file.c b/lib/nodes/file.c
index b8a62c004..d3ec27e60 100644
--- a/lib/nodes/file.c
+++ b/lib/nodes/file.c
@@ -205,7 +205,7 @@ int file_start(struct node *n)
 	f->uri = file_format_name(f->uri_tmpl, &now);
 
 	/* Open file */
-	flags = SAMPLE_ALL;
+	flags = SAMPLE_HAS_ALL;
 	if (f->flush)
 		flags |= IO_FLUSH;
 
diff --git a/lib/nodes/nanomsg.c b/lib/nodes/nanomsg.c
index 7c59944c1..1b2029204 100644
--- a/lib/nodes/nanomsg.c
+++ b/lib/nodes/nanomsg.c
@@ -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, SAMPLE_ALL);
+	ret = io_format_sprint(m->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_HAS_ALL);
 	if (ret <= 0)
 		return -1;
 
diff --git a/lib/nodes/shmem.c b/lib/nodes/shmem.c
index 7e532bd55..0f3c98e06 100644
--- a/lib/nodes/shmem.c
+++ b/lib/nodes/shmem.c
@@ -146,7 +146,7 @@ int shmem_write(struct node *n, struct sample *smps[], unsigned cnt)
 
 		/* Since the node isn't in shared memory, the source can't be accessed */
 		shared_smps[i]->source = NULL;
-		shared_smps[i]->has &= ~SAMPLE_SOURCE;
+		shared_smps[i]->flags &= ~SAMPLE_HAS_SOURCE;
 	}
 
 	pushed = shmem_int_write(&shm->intf, shared_smps, avail);
diff --git a/lib/nodes/signal.c b/lib/nodes/signal.c
index 1b2838a26..215078779 100644
--- a/lib/nodes/signal.c
+++ b/lib/nodes/signal.c
@@ -236,7 +236,7 @@ int signal_read(struct node *n, struct sample *smps[], unsigned cnt)
 
 	double running = time_delta(&s->started, &ts);
 
-	t->has = SAMPLE_ORIGIN | SAMPLE_VALUES | SAMPLE_SEQUENCE;
+	t->flags = SAMPLE_HAS_ORIGIN | SAMPLE_HAS_VALUES | SAMPLE_HAS_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 afcf84d5d..93df18f14 100644
--- a/lib/nodes/socket.c
+++ b/lib/nodes/socket.c
@@ -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, SAMPLE_ALL);
+	ret = io_format_sprint(s->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_HAS_ALL);
 	if (ret < 0)
 		return -1;
 
diff --git a/lib/nodes/stats.c b/lib/nodes/stats.c
index 30fc4a8a2..d34f6345c 100644
--- a/lib/nodes/stats.c
+++ b/lib/nodes/stats.c
@@ -131,7 +131,7 @@ int stats_node_read(struct node *n, struct sample *smps[], unsigned cnt)
 	task_wait_until_next_period(&sn->task);
 
 	smps[0]->length = MIN(STATS_COUNT * 6, smps[0]->capacity);
-	smps[0]->has = SAMPLE_VALUES;
+	smps[0]->flags = SAMPLE_HAS_VALUES;
 
 	for (int i = 0; i < 6 && (i+1)*STATS_METRICS <= smps[0]->length; i++) {
 		int tot = hist_total(&s->histograms[i]);
diff --git a/lib/nodes/websocket.c b/lib/nodes/websocket.c
index d6f55eb8d..465fee050 100644
--- a/lib/nodes/websocket.c
+++ b/lib/nodes/websocket.c
@@ -230,7 +230,7 @@ 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, SAMPLE_ALL);
+				io_format_sprint(c->format, c->buffers.send.buf + LWS_PRE, c->buffers.send.size - LWS_PRE, &wbytes, smps, pulled, SAMPLE_HAS_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);
 
@@ -285,7 +285,7 @@ int websocket_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, voi
 				/* Set receive timestamp */
 				for (int i = 0; i < recvd; i++) {
 					smps[i]->ts.received = ts_recv;
-					smps[i]->has |= SAMPLE_RECEIVED;
+					smps[i]->flags |= SAMPLE_HAS_RECEIVED;
 				}
 
 				ret = queue_signalled_push_many(&w->queue, (void **) smps, recvd);
diff --git a/lib/nodes/zeromq.c b/lib/nodes/zeromq.c
index 57a73cef5..19e2656e0 100644
--- a/lib/nodes/zeromq.c
+++ b/lib/nodes/zeromq.c
@@ -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, SAMPLE_ALL);
+	ret = io_format_sprint(z->format, data, sizeof(data), &wbytes, smps, cnt, SAMPLE_HAS_ALL);
 	if (ret <= 0)
 		return -1;
 
diff --git a/lib/sample.c b/lib/sample.c
index 0645f49b2..547f75904 100644
--- a/lib/sample.c
+++ b/lib/sample.c
@@ -96,7 +96,7 @@ 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->flags = src->flags;
 
 	dst->ts = src->ts;
 
@@ -115,13 +115,13 @@ int sample_copy_many(struct sample *dsts[], struct sample *srcs[], int cnt)
 
 int sample_cmp(struct sample *a, struct sample *b, double epsilon, int flags)
 {
-	if ((a->has & b->has & flags) != flags) {
-		printf("missing components: a=%#x, b=%#x, wanted=%#x\n", a->has, b->has, flags);
+	if ((a->flags & b->flags & flags) != flags) {
+		printf("flags: a=%#x, b=%#x, wanted=%#x\n", a->flags, b->flags, flags);
 		return -1;
 	}
 
 	/* Compare sequence no */
-	if (flags & SAMPLE_SEQUENCE) {
+	if (flags & SAMPLE_HAS_SEQUENCE) {
 		if (a->sequence != b->sequence) {
 			printf("sequence no: %d != %d\n", a->sequence, b->sequence);
 			return 2;
@@ -129,7 +129,7 @@ int sample_cmp(struct sample *a, struct sample *b, double epsilon, int flags)
 	}
 
 	/* Compare timestamp */
-	if (flags & SAMPLE_ORIGIN) {
+	if (flags & SAMPLE_HAS_ORIGIN) {
 		if (time_delta(&a->ts.origin, &b->ts.origin) > epsilon) {
 			printf("ts.origin: %f != %f\n", time_to_double(&a->ts.origin), time_to_double(&b->ts.origin));
 			return 3;
@@ -137,7 +137,7 @@ int sample_cmp(struct sample *a, struct sample *b, double epsilon, int flags)
 	}
 
 	/* Compare ID */
-	if (flags & SAMPLE_SOURCE) {
+	if (flags & SAMPLE_HAS_SOURCE) {
 		if (a->id != b->id) {
 			printf("id: %d != %d\n", a->id, b->id);
 			return 7;
@@ -145,7 +145,7 @@ int sample_cmp(struct sample *a, struct sample *b, double epsilon, int flags)
 	}
 
 	/* Compare data */
-	if (flags & SAMPLE_VALUES) {
+	if (flags & SAMPLE_HAS_VALUES) {
 		if (a->length != b->length) {
 			printf("length: %d != %d\n", a->length, b->length);
 			return 4;
diff --git a/src/hook.c b/src/hook.c
index 1d6838cf9..f2af04eb2 100644
--- a/src/hook.c
+++ b/src/hook.c
@@ -184,7 +184,7 @@ check:		if (optarg == endptr)
 	if (!p)
 		error("Unknown IO format '%s'", format);
 
-	ret = io_init(&io, &p->io, SAMPLE_ALL);
+	ret = io_init(&io, &p->io, SAMPLE_HAS_ALL);
 	if (ret)
 		error("Failed to initialize IO");
 
diff --git a/src/pipe.c b/src/pipe.c
index 735964928..e366b8154 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -296,7 +296,7 @@ check:		if (optarg == endptr)
 	if (!p)
 		error("Invalid format: %s", format);
 
-	ret = io_init(&io, &p->io, SAMPLE_ALL);
+	ret = io_init(&io, &p->io, SAMPLE_HAS_ALL);
 	if (ret)
 		error("Failed to initialize IO");
 
diff --git a/src/signal.c b/src/signal.c
index f65b681b3..7472f07a9 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 | (SAMPLE_ALL & ~SAMPLE_OFFSET));
+	ret = io_init(&io, &p->io, IO_FLUSH | (SAMPLE_HAS_ALL & ~SAMPLE_HAS_OFFSET));
 	if (ret)
 		error("Failed to initialize output");
 
diff --git a/src/test-cmp.c b/src/test-cmp.c
index c8698cf5e..cb4c6cc1e 100644
--- a/src/test-cmp.c
+++ b/src/test-cmp.c
@@ -76,7 +76,7 @@ int main(int argc, char *argv[])
 	/* Default values */
 	double epsilon = 1e-9;
 	char *format = "villas-human";
-	int flags = SAMPLE_SEQUENCE | SAMPLE_VALUES | SAMPLE_ORIGIN;
+	int flags = SAMPLE_HAS_SEQUENCE | SAMPLE_HAS_VALUES | SAMPLE_HAS_ORIGIN;
 
 	struct pool pool = { .state = STATE_DESTROYED };
 
@@ -88,13 +88,13 @@ int main(int argc, char *argv[])
 				epsilon = strtod(optarg, &endptr);
 				goto check;
 			case 'v':
-				flags &= ~SAMPLE_VALUES;
+				flags &= ~SAMPLE_HAS_VALUES;
 				break;
 			case 't':
-				flags &= ~SAMPLE_ORIGIN;
+				flags &= ~SAMPLE_HAS_ORIGIN;
 				break;
 			case 's':
-				flags &= ~SAMPLE_SEQUENCE;
+				flags &= ~SAMPLE_HAS_SEQUENCE;
 				break;
 			case 'f':
 				format = optarg;