diff --git a/CHANGES b/CHANGES
index e6dc8451d7..8e34f18ca0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5103.	[bug]		Add missing design by contract tests to dns_catz*.
+			[GL #748]
+
 5102.	[bug]		dnssec-coverage failed to use the default TTL when
 			checking KSK deletion times leading to a exception.
 			[GL #585]
diff --git a/lib/dns/catz.c b/lib/dns/catz.c
index 2a403f9585..3084f39b33 100644
--- a/lib/dns/catz.c
+++ b/lib/dns/catz.c
@@ -32,11 +32,19 @@
 #include <dns/view.h>
 #include <dns/zone.h>
 
+#define DNS_CATZ_ZONE_MAGIC ISC_MAGIC('c', 'a', 't', 'z')
+#define DNS_CATZ_ZONES_MAGIC ISC_MAGIC('c', 'a', 't', 's')
+#define DNS_CATZ_ENTRY_MAGIC ISC_MAGIC('c', 'a', 't', 'e')
+
+#define DNS_CATZ_ZONE_VALID(catz) ISC_MAGIC_VALID(catz, DNS_CATZ_ZONE_MAGIC)
+#define DNS_CATZ_ZONES_VALID(catzs) ISC_MAGIC_VALID(catzs, DNS_CATZ_ZONES_MAGIC)
+#define DNS_CATZ_ENTRY_VALID(entry) ISC_MAGIC_VALID(entry, DNS_CATZ_ENTRY_MAGIC)
 
 /*%
  * Single member zone in a catalog
  */
 struct dns_catz_entry {
+	unsigned int		magic;
 	dns_name_t		name;
 	dns_catz_options_t	opts;
 	isc_refcount_t		refs;
@@ -46,6 +54,7 @@ struct dns_catz_entry {
  * Catalog zone
  */
 struct dns_catz_zone {
+	unsigned int		magic;
 	dns_name_t		name;
 	dns_catz_zones_t	*catzs;
 	dns_rdata_t		soa;
@@ -58,7 +67,7 @@ struct dns_catz_zone {
 	dns_catz_options_t	defoptions;
 	dns_catz_options_t	zoneoptions;
 	isc_time_t		lastupdated;
-	bool		updatepending;
+	bool			updatepending;
 	uint32_t		version;
 
 	dns_db_t		*db;
@@ -67,8 +76,8 @@ struct dns_catz_zone {
 	isc_timer_t		*updatetimer;
 	isc_event_t		updateevent;
 
-	bool		active;
-	bool		db_registered;
+	bool			active;
+	bool			db_registered;
 
 	isc_refcount_t		refs;
 };
@@ -84,6 +93,7 @@ catz_process_zones_suboption(dns_catz_zone_t *zone, dns_rdataset_t *value,
  * Collection of catalog zones for a view
  */
 struct dns_catz_zones {
+	unsigned int			magic;
 	isc_ht_t			*zones;
 	isc_mem_t			*mctx;
 	isc_refcount_t			refs;
@@ -97,6 +107,9 @@ struct dns_catz_zones {
 
 void
 dns_catz_options_init(dns_catz_options_t *options) {
+
+	REQUIRE(options != NULL);
+
 	dns_ipkeylist_init(&options->masters);
 
 	options->allow_query = NULL;
@@ -112,6 +125,10 @@ dns_catz_options_init(dns_catz_options_t *options) {
 
 void
 dns_catz_options_free(dns_catz_options_t *options, isc_mem_t *mctx) {
+
+	REQUIRE(options != NULL);
+	REQUIRE(mctx != NULL);
+
 	if (options->masters.count != 0)
 		dns_ipkeylist_clear(mctx, &options->masters);
 	if (options->zonedir != NULL) {
@@ -128,6 +145,7 @@ isc_result_t
 dns_catz_options_copy(isc_mem_t *mctx, const dns_catz_options_t *src,
 		      dns_catz_options_t *dst)
 {
+	REQUIRE(mctx != NULL);
 	REQUIRE(src != NULL);
 	REQUIRE(dst != NULL);
 	REQUIRE(dst->masters.count == 0);
@@ -158,6 +176,10 @@ isc_result_t
 dns_catz_options_setdefault(isc_mem_t *mctx, const dns_catz_options_t *defaults,
 			    dns_catz_options_t *opts)
 {
+	REQUIRE(mctx != NULL);
+	REQUIRE(defaults != NULL);
+	REQUIRE(opts != NULL);
+
 	if (opts->masters.count == 0 && defaults->masters.count != 0)
 		dns_ipkeylist_copy(mctx, &defaults->masters, &opts->masters);
 
@@ -182,6 +204,7 @@ dns_catz_entry_new(isc_mem_t *mctx, const dns_name_t *domain,
 	dns_catz_entry_t *nentry;
 	isc_result_t result;
 
+	REQUIRE(mctx != NULL);
 	REQUIRE(nentryp != NULL && *nentryp == NULL);
 
 	nentry = isc_mem_get(mctx, sizeof(dns_catz_entry_t));
@@ -197,6 +220,7 @@ dns_catz_entry_new(isc_mem_t *mctx, const dns_name_t *domain,
 
 	dns_catz_options_init(&nentry->opts);
 	isc_refcount_init(&nentry->refs, 1);
+	nentry->magic = DNS_CATZ_ENTRY_MAGIC;
 	*nentryp = nentry;
 	return (ISC_R_SUCCESS);
 
@@ -207,6 +231,7 @@ cleanup:
 
 dns_name_t *
 dns_catz_entry_getname(dns_catz_entry_t *entry) {
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
 	return (&entry->name);
 }
 
@@ -217,6 +242,10 @@ dns_catz_entry_copy(dns_catz_zone_t *zone, const dns_catz_entry_t *entry,
 	isc_result_t result;
 	dns_catz_entry_t *nentry = NULL;
 
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
+	REQUIRE(nentryp != NULL && *nentryp == NULL);
+
 	result = dns_catz_entry_new(zone->catzs->mctx, &entry->name, &nentry);
 	if (result != ISC_R_SUCCESS)
 		return (result);
@@ -232,20 +261,28 @@ dns_catz_entry_copy(dns_catz_zone_t *zone, const dns_catz_entry_t *entry,
 
 void
 dns_catz_entry_attach(dns_catz_entry_t *entry, dns_catz_entry_t **entryp) {
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
 	REQUIRE(entryp != NULL && *entryp == NULL);
+
 	isc_refcount_increment(&entry->refs);
 	*entryp = entry;
 }
 
 void
 dns_catz_entry_detach(dns_catz_zone_t *zone, dns_catz_entry_t **entryp) {
-	REQUIRE(entryp != NULL && *entryp != NULL);
-	dns_catz_entry_t *entry = *entryp;
+	dns_catz_entry_t *entry;
+
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
+	REQUIRE(entryp != NULL);
+	entry = *entryp;
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
+
 	*entryp = NULL;
 
 	if (isc_refcount_decrement(&entry->refs) == 1) {
-		isc_refcount_destroy(&entry->refs);
 		isc_mem_t *mctx = zone->catzs->mctx;
+		entry->magic = 0;
+		isc_refcount_destroy(&entry->refs);
 		dns_catz_options_free(&entry->opts, mctx);
 		if (dns_name_dynamic(&entry->name))
 			dns_name_free(&entry->name, mctx);
@@ -255,6 +292,7 @@ dns_catz_entry_detach(dns_catz_zone_t *zone, dns_catz_entry_t **entryp) {
 
 bool
 dns_catz_entry_validate(const dns_catz_entry_t *entry) {
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
 	UNUSED(entry);
 
 	return (true);
@@ -264,6 +302,9 @@ bool
 dns_catz_entry_cmp(const dns_catz_entry_t *ea, const dns_catz_entry_t *eb) {
 	isc_region_t ra, rb;
 
+	REQUIRE(DNS_CATZ_ENTRY_VALID(ea));
+	REQUIRE(DNS_CATZ_ENTRY_VALID(eb));
+
 	if (ea == eb)
 		return (true);
 
@@ -304,21 +345,21 @@ dns_catz_entry_cmp(const dns_catz_entry_t *ea, const dns_catz_entry_t *eb) {
 
 dns_name_t *
 dns_catz_zone_getname(dns_catz_zone_t *zone) {
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 
 	return (&zone->name);
 }
 
 dns_catz_options_t *
 dns_catz_zone_getdefoptions(dns_catz_zone_t *zone) {
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 
 	return (&zone->defoptions);
 }
 
 void
 dns_catz_zone_resetdefoptions(dns_catz_zone_t *zone) {
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 
 	dns_catz_options_free(&zone->defoptions, zone->catzs->mctx);
 	dns_catz_options_init(&zone->defoptions);
@@ -335,8 +376,8 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone) {
 	char zname[DNS_NAME_FORMATSIZE];
 	dns_catz_zoneop_fn_t addzone, modzone, delzone;
 
-	REQUIRE(target != NULL);
-	REQUIRE(newzone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(newzone));
+	REQUIRE(DNS_CATZ_ZONE_VALID(target));
 
 	/* TODO verify the new zone first! */
 
@@ -391,9 +432,9 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone) {
 	     result = delcur ? isc_ht_iter_delcurrent_next(iter1) :
 			     isc_ht_iter_next(iter1))
 	{
-		dns_catz_entry_t *nentry;
-		dns_catz_entry_t *oentry;
-		unsigned char * key;
+		dns_catz_entry_t *nentry = NULL;
+		dns_catz_entry_t *oentry = NULL;
+		unsigned char * key = NULL;
 		size_t keysize;
 		delcur = false;
 
@@ -464,7 +505,7 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone) {
 	     result == ISC_R_SUCCESS;
 	     result = isc_ht_iter_delcurrent_next(iter2))
 	{
-		dns_catz_entry_t *entry;
+		dns_catz_entry_t *entry = NULL;
 		isc_ht_iter_current(iter2, (void **) &entry);
 
 		dns_name_format(&entry->name, zname, DNS_NAME_FORMATSIZE);
@@ -487,7 +528,7 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone) {
 	     result == ISC_R_SUCCESS;
 	     result = isc_ht_iter_delcurrent_next(iteradd))
 	{
-		dns_catz_entry_t *entry;
+		dns_catz_entry_t *entry = NULL;
 		isc_ht_iter_current(iteradd, (void **) &entry);
 
 		dns_name_format(&entry->name, zname, DNS_NAME_FORMATSIZE);
@@ -506,7 +547,7 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone) {
 	     result == ISC_R_SUCCESS;
 	     result = isc_ht_iter_delcurrent_next(itermod))
 	{
-		dns_catz_entry_t *entry;
+		dns_catz_entry_t *entry = NULL;
 		isc_ht_iter_current(itermod, (void **) &entry);
 
 		dns_name_format(&entry->name, zname, DNS_NAME_FORMATSIZE);
@@ -540,7 +581,6 @@ cleanup:
 	if (tomod != NULL)
 		isc_ht_destroy(&tomod);
 	return (result);
-
 }
 
 isc_result_t
@@ -575,6 +615,7 @@ dns_catz_new_zones(dns_catz_zones_t **catzsp, dns_catz_zonemodmethods_t *zmm,
 	result = isc_task_create(taskmgr, 0, &new_zones->updater);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup_ht;
+	new_zones->magic = DNS_CATZ_ZONES_MAGIC;
 
 	*catzsp = new_zones;
 	return (ISC_R_SUCCESS);
@@ -591,7 +632,7 @@ dns_catz_new_zones(dns_catz_zones_t **catzsp, dns_catz_zonemodmethods_t *zmm,
 
 void
 dns_catz_catzs_set_view(dns_catz_zones_t *catzs, dns_view_t *view) {
-	REQUIRE(catzs != NULL);
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 	REQUIRE(view != NULL);
 	/* Either it's a new one or it's being reconfigured. */
 	REQUIRE(catzs->view == NULL || !strcmp(catzs->view->name, view->name));
@@ -606,7 +647,9 @@ dns_catz_new_zone(dns_catz_zones_t *catzs, dns_catz_zone_t **zonep,
 	isc_result_t result;
 	dns_catz_zone_t *new_zone;
 
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 	REQUIRE(zonep != NULL && *zonep == NULL);
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 
 	new_zone = isc_mem_get(catzs->mctx, sizeof(*new_zone));
 	if (new_zone == NULL)
@@ -643,6 +686,7 @@ dns_catz_new_zone(dns_catz_zones_t *catzs, dns_catz_zone_t **zonep,
 	new_zone->db_registered = false;
 	new_zone->version = (uint32_t)(-1);
 	isc_refcount_init(&new_zone->refs, 1);
+	new_zone->magic = DNS_CATZ_ZONE_MAGIC;
 
 	*zonep = new_zone;
 
@@ -666,9 +710,10 @@ dns_catz_add_zone(dns_catz_zones_t *catzs, const dns_name_t *name,
 	isc_result_t result, tresult;
 	char zname[DNS_NAME_FORMATSIZE];
 
-	REQUIRE(catzs != NULL);
-	REQUIRE(name != NULL);
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 	REQUIRE(zonep != NULL && *zonep == NULL);
+
 	dns_name_format(name, zname, DNS_NAME_FORMATSIZE);
 	isc_log_write(dns_lctx, DNS_LOGCATEGORY_GENERAL,
 		      DNS_LOGMODULE_MASTER, ISC_LOG_DEBUG(3),
@@ -706,7 +751,10 @@ dns_catz_add_zone(dns_catz_zones_t *catzs, const dns_name_t *name,
 dns_catz_zone_t *
 dns_catz_get_zone(dns_catz_zones_t *catzs, const dns_name_t *name) {
 	isc_result_t result;
-	dns_catz_zone_t *found;
+	dns_catz_zone_t *found = NULL;
+
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 
 	result = isc_ht_find(catzs->zones, name->ndata, name->length,
 			     (void **) &found);
@@ -718,6 +766,7 @@ dns_catz_get_zone(dns_catz_zones_t *catzs, const dns_name_t *name) {
 
 void
 dns_catz_catzs_attach(dns_catz_zones_t *catzs, dns_catz_zones_t **catzsp) {
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 	REQUIRE(catzsp != NULL && *catzsp == NULL);
 
 	isc_refcount_increment(&catzs->refs);
@@ -739,6 +788,7 @@ dns_catz_zone_detach(dns_catz_zone_t **zonep) {
 	*zonep = NULL;
 
 	if (isc_refcount_decrement(&zone->refs) == 1) {
+		isc_mem_t *mctx = zone->catzs->mctx;
 		isc_refcount_destroy(&zone->refs);
 		if (zone->entries != NULL) {
 			isc_ht_iter_t *iter = NULL;
@@ -749,7 +799,7 @@ dns_catz_zone_detach(dns_catz_zone_t **zonep) {
 			     result == ISC_R_SUCCESS;
 			     result = isc_ht_iter_delcurrent_next(iter))
 			{
-				dns_catz_entry_t *entry;
+				dns_catz_entry_t *entry = NULL;
 
 				isc_ht_iter_current(iter, (void **) &entry);
 				dns_catz_entry_detach(zone, &entry);
@@ -761,7 +811,7 @@ dns_catz_zone_detach(dns_catz_zone_t **zonep) {
 			INSIST(isc_ht_count(zone->entries) == 0);
 			isc_ht_destroy(&zone->entries);
 		}
-		isc_mem_t *mctx = zone->catzs->mctx;
+		zone->magic = 0;
 		isc_timer_detach(&zone->updatetimer);
 		if (zone->db_registered == true) {
 			INSIST(dns_db_updatenotify_unregister(
@@ -794,6 +844,7 @@ dns_catz_catzs_detach(dns_catz_zones_t **catzsp) {
 	*catzsp = NULL;
 
 	if (isc_refcount_decrement(&catzs->refs) == 1) {
+		catzs->magic = 0;
 		isc_task_destroy(&catzs->updater);
 		isc_mutex_destroy(&catzs->lock);
 		if (catzs->zones != NULL) {
@@ -804,7 +855,7 @@ dns_catz_catzs_detach(dns_catz_zones_t **catzsp) {
 			for (result = isc_ht_iter_first(iter);
 			     result == ISC_R_SUCCESS;)
 			{
-				dns_catz_zone_t *zone;
+				dns_catz_zone_t *zone = NULL;
 				isc_ht_iter_current(iter, (void **) &zone);
 				result = isc_ht_iter_delcurrent_next(iter);
 				dns_catz_zone_detach(&zone);
@@ -861,9 +912,9 @@ catz_process_zones(dns_catz_zone_t *zone, dns_rdataset_t *value,
 	dns_label_t mhash;
 	dns_name_t opt;
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(DNS_RDATASET_VALID(value));
-	REQUIRE(name != NULL);
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 
 	if (value->rdclass != dns_rdataclass_in)
 		return (ISC_R_FAILURE);
@@ -954,7 +1005,7 @@ catz_process_version(dns_catz_zone_t *zone, dns_rdataset_t *value) {
 	uint32_t tversion;
 	char t[16];
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(DNS_RDATASET_VALID(value));
 
 	if (value->rdclass != dns_rdataclass_in ||
@@ -1019,11 +1070,11 @@ catz_process_masters(dns_catz_zone_t *zone, dns_ipkeylist_t *ipkl,
 	unsigned int rcount;
 	unsigned int i;
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(ipkl != NULL);
 	REQUIRE(DNS_RDATASET_VALID(value));
 	REQUIRE(dns_rdataset_isassociated(value));
-	REQUIRE(name != NULL);
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 
 	mctx = zone->catzs->mctx;
 	memset(&rdata_a, 0, sizeof(rdata_a));
@@ -1203,7 +1254,7 @@ catz_process_apl(dns_catz_zone_t *zone, isc_buffer_t **aclbp,
 	isc_buffer_t *aclb = NULL;
 	unsigned char buf[256]; /* larger than INET6_ADDRSTRLEN */
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(aclbp != NULL);
 	REQUIRE(*aclbp == NULL);
 	REQUIRE(DNS_RDATASET_VALID(value));
@@ -1280,9 +1331,10 @@ catz_process_zones_suboption(dns_catz_zone_t *zone, dns_rdataset_t *value,
 	dns_name_t prefix;
 	catz_opt_t opt;
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(mhash != NULL);
 	REQUIRE(DNS_RDATASET_VALID(value));
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 
 	if (name->labels == 0)
 		return (ISC_R_FAILURE);
@@ -1338,8 +1390,8 @@ catz_process_value(dns_catz_zone_t *zone, dns_name_t *name,
 	dns_name_t prefix;
 	catz_opt_t opt;
 
-	REQUIRE(zone != NULL);
-	REQUIRE(name != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
+	REQUIRE(ISC_MAGIC_VALID(name, DNS_NAME_MAGIC));
 	REQUIRE(DNS_RDATASET_VALID(rdataset));
 
 	dns_name_getlabel(name, name->labels - 1, &option);
@@ -1384,8 +1436,9 @@ dns_catz_update_process(dns_catz_zones_t *catzs, dns_catz_zone_t *zone,
 	dns_rdata_soa_t soa;
 	dns_name_t prefix;
 
-	REQUIRE(catzs != NULL);
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
+	REQUIRE(ISC_MAGIC_VALID(src_name, DNS_NAME_MAGIC));
 
 	nrres = dns_name_fullcompare(src_name, &zone->name, &order, &nlabels);
 	if (nrres == dns_namereln_equal) {
@@ -1444,7 +1497,7 @@ dns_catz_generate_masterfilename(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
 	isc_result_t result;
 	size_t rlen;
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(entry != NULL);
 	REQUIRE(buffer != NULL && *buffer != NULL);
 
@@ -1530,7 +1583,7 @@ dns_catz_generate_zonecfg(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
 	char pbuf[sizeof("65535")]; /* used both for port number and DSCP */
 	char zname[DNS_NAME_FORMATSIZE];
 
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(entry != NULL);
 	REQUIRE(buf != NULL && *buf == NULL);
 
@@ -1642,7 +1695,7 @@ dns_catz_update_taskaction(isc_task_t *task, isc_event_t *event) {
 
 	REQUIRE(event != NULL);
 	zone = event->ev_arg;
-	REQUIRE(zone != NULL);
+	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 
 	LOCK(&zone->catzs->lock);
 	zone->updatepending = false;
@@ -1754,7 +1807,7 @@ dns_catz_update_from_db(dns_db_t *db, dns_catz_zones_t *catzs) {
 	uint32_t vers;
 
 	REQUIRE(DNS_DB_VALID(db));
-	REQUIRE(catzs != NULL);
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 
 	/*
 	 * Create a new catz in the same context as current catz.
@@ -1927,9 +1980,8 @@ void
 dns_catz_prereconfig(dns_catz_zones_t *catzs) {
 	isc_result_t result;
 	isc_ht_iter_t *iter = NULL;
-	dns_catz_zone_t *zone;
 
-	REQUIRE(catzs != NULL);
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 
 	result = isc_ht_iter_create(catzs->zones, &iter);
 	INSIST(result == ISC_R_SUCCESS);
@@ -1937,6 +1989,7 @@ dns_catz_prereconfig(dns_catz_zones_t *catzs) {
 	     result == ISC_R_SUCCESS;
 	     result = isc_ht_iter_next(iter))
 	{
+		dns_catz_zone_t *zone = NULL;
 		isc_ht_iter_current(iter, (void **) &zone);
 		zone->active = false;
 	}
@@ -1949,7 +2002,8 @@ dns_catz_postreconfig(dns_catz_zones_t *catzs) {
 	isc_result_t result;
 	dns_catz_zone_t *newzone = NULL;
 	isc_ht_iter_t *iter = NULL;
-	dns_catz_zone_t *zone;
+
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 
 	LOCK(&catzs->lock);
 	result = isc_ht_iter_create(catzs->zones, &iter);
@@ -1957,6 +2011,8 @@ dns_catz_postreconfig(dns_catz_zones_t *catzs) {
 	for (result = isc_ht_iter_first(iter);
 	     result == ISC_R_SUCCESS;)
 	{
+		dns_catz_zone_t *zone = NULL;
+
 		isc_ht_iter_current(iter, (void **) &zone);
 		if (zone->active == false) {
 			char cname[DNS_NAME_FORMATSIZE];
@@ -1992,5 +2048,6 @@ dns_catz_postreconfig(dns_catz_zones_t *catzs) {
 
 isc_result_t
 dns_catz_get_iterator(dns_catz_zone_t *catz, isc_ht_iter_t **itp) {
+	REQUIRE(DNS_CATZ_ZONE_VALID(catz));
 	return (isc_ht_iter_create(catz->entries, itp));
 }
diff --git a/lib/dns/include/dns/catz.h b/lib/dns/include/dns/catz.h
index bfcf6e4d15..cf466d25da 100644
--- a/lib/dns/include/dns/catz.h
+++ b/lib/dns/include/dns/catz.h
@@ -78,7 +78,7 @@ dns_catz_options_init(dns_catz_options_t *options);
  * Initialize 'options' to NULL values.
  *
  * Requires:
- * \li	options to be non NULL
+ * \li	'options' to be non NULL.
  */
 
 void
@@ -87,20 +87,20 @@ dns_catz_options_free(dns_catz_options_t *options, isc_mem_t *mctx);
  * Free 'options' contents into 'mctx'. ('options' itself is not freed.)
  *
  * Requires:
- * \li	options to be non NULL
- * \li	mctx to be a valid memory context
+ * \li	'options' to be non NULL.
+ * \li	'mctx' to be a valid memory context.
  */
 
 isc_result_t
 dns_catz_options_copy(isc_mem_t *mctx, const dns_catz_options_t *opts,
 		      dns_catz_options_t *nopts);
 /*%<
- * Duplicate 'opts' into 'nopts', allocating space from 'mctx'
+ * Duplicate 'opts' into 'nopts', allocating space from 'mctx'.
  *
  * Requires:
- * \li	'mctx' to be a valid memory context
- * \li	'options' to be non NULL and valid options
- * \li	'nopts' to be non NULL
+ * \li	'mctx' to be a valid memory context.
+ * \li	'options' to be non NULL and valid options.
+ * \li	'nopts' to be non NULL.
  */
 
 isc_result_t
@@ -110,9 +110,9 @@ dns_catz_options_setdefault(isc_mem_t *mctx, const dns_catz_options_t *defaults,
  * Replace empty values in 'opts' with values from 'defaults'
  *
  * Requires:
- * \li	mctx to be a valid memory context
- * \li	defaults to be non NULL and valid options
- * \li	opts to be non NULL
+ * \li	'mctx' to be a valid memory context.
+ * \li	'defaults' to be non NULL and valid options.
+ * \li	'opts' to be non NULL.
  */
 
 dns_name_t *
@@ -121,10 +121,10 @@ dns_catz_entry_getname(dns_catz_entry_t *entry);
  * Get domain name for 'entry'
  *
  * Requires:
- * \li	entry to be non NULL
+ * \li	'entry' to be non NULL.
  *
  * Returns:
- * \li	domain name for entry
+ * \li	domain name for entry.
  */
 
 isc_result_t
@@ -134,9 +134,9 @@ dns_catz_entry_new(isc_mem_t *mctx, const dns_name_t *domain,
  * Allocate a new catz_entry on 'mctx', with the name 'domain'
  *
  * Requires:
- * \li	mctx to be a valid memory context
- * \li	domain to be valid dns_name or NULL
- * \li	nentryp to be non NULL, *nentryp to be NULL
+ * \li	'mctx' to be a valid memory context.
+ * \li	'domain' to be valid dns_name or NULL.
+ * \li	'nentryp' to be non NULL, *nentryp to be NULL.
  *
  * Returns:
  * \li	ISC_R_SUCCESS on success
@@ -150,9 +150,9 @@ dns_catz_entry_copy(dns_catz_zone_t *zone, const dns_catz_entry_t *entry,
  * Allocate a new catz_entry and deep copy 'entry' into 'nentryp'.
  *
  * Requires:
- * \li	mctx to be a valid memory context
- * \li	entry to be non NULL
- * \li	nentryp to be non NULL, *nentryp to be NULL
+ * \li	'mctx' to be a valid memory context.
+ * \li	'entry' to be non NULL.
+ * \li	'nentryp' to be non NULL, *nentryp to be NULL.
  *
  * Returns:
  * \li	ISC_R_SUCCESS on success
@@ -165,8 +165,8 @@ dns_catz_entry_attach(dns_catz_entry_t *entry, dns_catz_entry_t **entryp);
  * Attach an entry
  *
  * Requires:
- * \li	entry is not NULL
- * \li	entryp is not NULL, *entryp is NULL
+ * \li	'entry' is a valid dns_catz_entry_t.
+ * \li	'entryp' is not NULL and '*entryp' is NULL.
  */
 
 void
@@ -175,8 +175,8 @@ dns_catz_entry_detach(dns_catz_zone_t *zone, dns_catz_entry_t **entryp);
  * Detach an entry, free if no further references
  *
  * Requires:
- * \li	zone is not NULL
- * \li	entryp is not NULL, *entryp is not NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
+ * \li	'entryp' is not NULL and '*entryp' is not NULL.
  */
 
 bool
@@ -184,6 +184,9 @@ dns_catz_entry_validate(const dns_catz_entry_t *entry);
 /*%<
  * Validate whether entry is correct.
  * (NOT YET IMPLEMENTED: always returns true)
+ *
+ * Requires:
+ *\li	'entry' is a valid dns_catz_entry_t.
  */
 
 bool
@@ -192,12 +195,12 @@ dns_catz_entry_cmp(const dns_catz_entry_t *ea, const dns_catz_entry_t *eb);
  * Deep compare two entries
  *
  * Requires:
- * \li	ea is not NULL
- * \li	eb is not NULL
+ * \li	'ea' is a valid dns_catz_entry_t.
+ * \li	'eb' is a valid dns_catz_entry_t.
  *
  * Returns:
- * \li true if entries are the same
- * \li false if the entries differ
+ * \li 'true' if entries are the same.
+ * \li 'false' if the entries differ.
  */
 
 void
@@ -206,8 +209,8 @@ dns_catz_zone_attach(dns_catz_zone_t *zone, dns_catz_zone_t **zonep);
  * Attach a catzone
  *
  * Requires:
- * \li	zone is not NULL
- * \li	zonep is not NULL, *zonep is NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
+ * \li	'zonep' is not NULL and '*zonep' is NULL.
  */
 
 void
@@ -216,7 +219,7 @@ dns_catz_zone_detach(dns_catz_zone_t** zonep);
  * Detach a zone, free if no further references
  *
  * Requires:
- * \li	zonep is not NULL, *zonep is not NULL
+ * \li	'zonep' is not NULL and '*zonep' is not NULL.
  */
 
 isc_result_t
@@ -226,9 +229,9 @@ dns_catz_new_zone(dns_catz_zones_t *catzs, dns_catz_zone_t **zonep,
  * Allocate a new catz zone on catzs mctx
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	zonep is not NULL, *zonep is NULL
- * \li	name is not NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'zonep' is not NULL and '*zonep' is NULL.
+ * \li	'name' is a valid dns_name_t.
  *
  */
 
@@ -238,7 +241,7 @@ dns_catz_zone_getname(dns_catz_zone_t *zone);
  * Get catalog zone name
  *
  * Requires:
- * \li	zone is not NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
  */
 
 dns_catz_options_t *
@@ -247,7 +250,7 @@ dns_catz_zone_getdefoptions(dns_catz_zone_t *zone);
  * Get default member zone options for catalog zone 'zone'
  *
  * Requires:
- * \li	zone is not NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
  */
 
 void
@@ -257,7 +260,7 @@ dns_catz_zone_resetdefoptions(dns_catz_zone_t *zone);
  * the default values.
  *
  * Requires:
- * \li	zone is not NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
  */
 
 isc_result_t
@@ -267,8 +270,8 @@ dns_catz_zones_merge(dns_catz_zone_t *target, dns_catz_zone_t *newzone);
  * (from zone->catzs->zmm) for appropriate member zones.
  *
  * Requires:
- * \li	orig is not NULL
- * \li	newzone is not NULL, *newzone is not NULL
+ * \li	'orig' is a valid dns_catz_zone_t.
+ * \li	'newzone' is not NULL and '*newzone' is not NULL.
  *
  */
 
@@ -280,10 +283,10 @@ dns_catz_update_process(dns_catz_zones_t *catzs, dns_catz_zone_t *zone,
  * record name.
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	zone is not NULL
- * \li	src_name is not NULL
- * \li	rdataset is valid
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'zone' is a valid dns_catz_zone_t.
+ * \li	'src_name' is a valid dns_name_t.
+ * \li	'rdataset' is valid rdataset.
  */
 
 isc_result_t
@@ -297,9 +300,9 @@ dns_catz_generate_masterfilename(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
  * __catz__unique_hash_generated_from_the_above.db
  *
  * Requires:
- * \li	zone is not NULL
- * \li	entry is not NULL
- * \li	buffer is not NULL and *buffer is not NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
+ * \li	'entry' is a valid dns_catz_entry_t.
+ * \li	'buffer' is not NULL and '*buffer' is not NULL.
  */
 
 isc_result_t
@@ -310,10 +313,9 @@ dns_catz_generate_zonecfg(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
  * it into *buf. buf might be reallocated.
  *
  * Requires:
- * \li	zone is not NULL
- * \li	entry is not NULL
- * \li	buf is not NULL
- * \li	*buf is NULL
+ * \li	'zone' is a valid dns_catz_zone_t.
+ * \li	'entry' is a valid dns_catz_entry_t.
+ * \li	'buf' is not NULL and '*buf' is NULL.
  *
  */
 
@@ -340,8 +342,8 @@ dns_catz_new_zones(dns_catz_zones_t **catzsp, dns_catz_zonemodmethods_t *zmm,
  * for a view.
  *
  * Requires:
- * \li catzsp is not NULL, *catzsp is NULL
- * \li zmm is not NULL
+ * \li 'catzsp' is not NULL and '*catzsp' is NULL.
+ * \li 'zmm' is not NULL.
  *
  */
 
@@ -352,9 +354,9 @@ dns_catz_add_zone(dns_catz_zones_t *catzs, const dns_name_t *name,
  * Allocate a new catz named 'name' and put it in 'catzs' collection.
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	name is not NULL
- * \li	zonep is not NULL, *zonep is NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'name' is a valid dns_name_t.
+ * \li	'zonep' is not NULL and *zonep is NULL.
  *
  */
 
@@ -364,37 +366,37 @@ dns_catz_get_zone(dns_catz_zones_t *catzs, const dns_name_t *name);
  * Returns a zone named 'name' from collection 'catzs'
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	name is not NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'name' is a valid dns_name_t.
  */
 
 void
 dns_catz_catzs_attach(dns_catz_zones_t *catzs, dns_catz_zones_t **catzsp);
 /*%<
- * Attach 'catzs' to 'catzsp'
+ * Attach 'catzs' to 'catzsp'.
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	catzsp is not NULL, *catzsp is NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'catzsp' is not NULL and *catzsp is NULL.
  */
 
 void
 dns_catz_catzs_detach(dns_catz_zones_t **catzsp);
 /*%<
- * Detach 'catzsp', free if no further references
+ * Detach 'catzsp', free if no further references.
  *
  * Requires:
- * \li	catzsp is not NULL, *catzsp is not NULL
+ * \li	'catzsp' is not NULL and *catzsp is not NULL.
  */
 
 void
 dns_catz_catzs_set_view(dns_catz_zones_t *catzs, dns_view_t *view);
 /*%<
- * Set a view for catzs
+ * Set a view for 'catzs'.
  *
  * Requires:
- * \li	catzs is not NULL
- * \li	catzs->view is NULL or catzs->view == view
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'catzs->view' is NULL or 'catzs->view' == 'view'.
  */
 
 
@@ -409,17 +411,17 @@ dns_catz_dbupdate_callback(dns_db_t *db, void *fn_arg);
  * If there is an update scheduled it replaces old db version with a new one.
  *
  * Requires:
- * \li	db is a valid database
- * \li	fn_arg is not NULL (casted to dns_catz_zones_t*)
+ * \li	'db' is a valid database.
+ * \li	'fn_arg' is not NULL (casted to dns_catz_zones_t*).
  */
 
 void
 dns_catz_update_taskaction(isc_task_t *task, isc_event_t *event);
 /*%<
- * Task that launches dns_catz_update_from_db
+ * Task that launches dns_catz_update_from_db.
  *
  * Requires:
- * \li	event is not NULL
+ * \li	'event' is not NULL.
  */
 
 void
@@ -430,8 +432,8 @@ dns_catz_update_from_db(dns_db_t *db, dns_catz_zones_t *catzs);
  * then merges new catz into old catz.
  *
  * Requires:
- * \li	db is a valid DB
- * \li	catzs is not NULL
+ * \li	'db' is a valid DB.
+ * \li	'catzs' is a valid dns_catz_zones_t.
  *
  */
 
@@ -441,7 +443,7 @@ dns_catz_prereconfig(dns_catz_zones_t *catzs);
  * Called before reconfig, clears 'active' flag on all the zones in set
  *
  * Requires:
- * \li	catzs is not NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
  *
  */
 
@@ -452,7 +454,7 @@ dns_catz_postreconfig(dns_catz_zones_t *catzs);
  * inactive and force reload of those with changed configuration.
  *
  * Requires:
- * \li	catzs is not NULL
+ * \li	'catzs' is a valid dns_catz_zones_t.
  */
 
 isc_result_t
@@ -460,6 +462,10 @@ dns_catz_get_iterator(dns_catz_zone_t *catz, isc_ht_iter_t **itp);
 /*%<
  * Get the hashtable iterator on catalog zone members, point '*itp' to it.
  *
+ * Requires:
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ * \li	'itp' is not NULL and '*itp' is NULL.
+ *
  * Returns:
  * \li #ISC_R_SUCCESS		-- success
  * \li Any other value		-- failure
diff --git a/lib/dns/rpz.c b/lib/dns/rpz.c
index 6fcd5dca17..e3b2f25698 100644
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -1779,7 +1779,7 @@ finish_update(dns_rpz_zone_t *rpz) {
 	     result = isc_ht_iter_delcurrent_next(iter))
 	{
 		isc_region_t region;
-		unsigned char *key;
+		unsigned char *key = NULL;
 		size_t keysize;
 
 		isc_ht_iter_currentkey(iter, &key, &keysize);
diff --git a/lib/isc/ht.c b/lib/isc/ht.c
index 0925a59e19..5369aadadb 100644
--- a/lib/isc/ht.c
+++ b/lib/isc/ht.c
@@ -162,6 +162,7 @@ isc_ht_find(const isc_ht_t *ht, const unsigned char *key,
 
 	REQUIRE(ISC_HT_VALID(ht));
 	REQUIRE(key != NULL && keysize > 0);
+	REQUIRE(valuep == NULL || *valuep == NULL);
 
 	hash = isc_hash_function(key, keysize, true, NULL);
 	node = ht->table[hash & ht->mask];
@@ -327,6 +328,8 @@ void
 isc_ht_iter_current(isc_ht_iter_t *it, void **valuep) {
 	REQUIRE(it != NULL);
 	REQUIRE(it->cur != NULL);
+	REQUIRE(valuep != NULL && *valuep == NULL);
+
 	*valuep = it->cur->value;
 }
 
@@ -335,6 +338,8 @@ isc_ht_iter_currentkey(isc_ht_iter_t *it, unsigned char **key, size_t *keysize)
 {
 	REQUIRE(it != NULL);
 	REQUIRE(it->cur != NULL);
+	REQUIRE(key != NULL && *key == NULL);
+
 	*key = it->cur->key;
 	*keysize = it->cur->keysize;
 }
diff --git a/lib/isc/include/isc/ht.h b/lib/isc/include/isc/ht.h
index 608707b84b..3a44e150b5 100644
--- a/lib/isc/include/isc/ht.h
+++ b/lib/isc/include/isc/ht.h
@@ -27,10 +27,9 @@ typedef struct isc_ht_iter isc_ht_iter_t;
  * Initialize hashtable at *htp, using memory context and size of (1<<bits)
  *
  * Requires:
- *\li	htp is not NULL
- *\li	*htp is NULL
- *\li	mctx is a valid memory context
- *\li	bits >=1 && bits <=32
+ *\li	'htp' is not NULL and '*htp' is NULL.
+ *\li	'mctx' is a valid memory context.
+ *\li	'bits' >=1 and 'bits' <=32
  *
  * Returns:
  *\li	#ISC_R_NOMEMORY		-- not enough memory to create pool
@@ -43,7 +42,7 @@ isc_ht_init(isc_ht_t **htp, isc_mem_t *mctx, uint8_t bits);
  * Destroy hashtable, freeing everything
  *
  * Requires:
- * \li	*htp is valid hashtable
+ * \li	'*htp' is valid hashtable
  */
 void
 isc_ht_destroy(isc_ht_t **htp);
@@ -53,7 +52,7 @@ isc_ht_destroy(isc_ht_t **htp);
  * set its value to 'value'
  *
  * Requires:
- *\li	ht is a valid hashtable
+ *\li	'ht' is a valid hashtable
  *
  * Returns:
  *\li	#ISC_R_NOMEMORY		-- not enough memory to create pool
@@ -83,6 +82,7 @@ isc_ht_find(const isc_ht_t *ht, const unsigned char *key,
 
 /*%
  * Delete node from hashtable
+ *
  * Requires:
  *\li	ht is a valid hashtable
  *
@@ -95,12 +95,19 @@ isc_ht_delete(isc_ht_t *ht, const unsigned char *key, uint32_t keysize);
 
 /*%
  * Create an iterator for the hashtable; point '*itp' to it.
+ *
+ * Requires:
+ *\li	'ht' is a valid hashtable
+ *\li	'itp' is non NULL and '*itp' is NULL.
  */
 isc_result_t
 isc_ht_iter_create(isc_ht_t *ht, isc_ht_iter_t **itp);
 
 /*%
  * Destroy the iterator '*itp', set it to NULL
+ *
+ * Requires:
+ *\li	'itp' is non NULL and '*itp' is non NULL.
  */
 void
 isc_ht_iter_destroy(isc_ht_iter_t **itp);
@@ -108,6 +115,9 @@ isc_ht_iter_destroy(isc_ht_iter_t **itp);
 /*%
  * Set an iterator to the first entry.
  *
+ * Requires:
+ *\li	'it' is non NULL.
+ *
  * Returns:
  * \li 	#ISC_R_SUCCESS	-- success
  * \li	#ISC_R_NOMORE	-- no data in the hashtable
@@ -118,6 +128,9 @@ isc_ht_iter_first(isc_ht_iter_t *it);
 /*%
  * Set an iterator to the next entry.
  *
+ * Requires:
+ *\li	'it' is non NULL.
+ *
  * Returns:
  * \li 	#ISC_R_SUCCESS	-- success
  * \li	#ISC_R_NOMORE	-- end of hashtable reached
@@ -128,6 +141,9 @@ isc_ht_iter_next(isc_ht_iter_t *it);
 /*%
  * Delete current entry and set an iterator to the next entry.
  *
+ * Requires:
+ *\li	'it' is non NULL.
+ *
  * Returns:
  * \li 	#ISC_R_SUCCESS	-- success
  * \li	#ISC_R_NOMORE	-- end of hashtable reached
@@ -138,6 +154,10 @@ isc_ht_iter_delcurrent_next(isc_ht_iter_t *it);
 
 /*%
  * Set 'value' to the current value under the iterator
+ *
+ * Requires:
+ *\li	'it' is non NULL.
+ *\li   'valuep' is non NULL and '*valuep' is NULL.
  */
 void
 isc_ht_iter_current(isc_ht_iter_t *it, void **valuep);
@@ -145,6 +165,11 @@ isc_ht_iter_current(isc_ht_iter_t *it, void **valuep);
 /*%
  * Set 'key' and 'keysize to the current key and keysize for the value
  * under the iterator
+ *
+ * Requires:
+ *\li	'it' is non NULL.
+ *\li   'key' is non NULL and '*key' is NULL.
+ *\li	'keysize' is non NULL.
  */
 void
 isc_ht_iter_currentkey(isc_ht_iter_t *it, unsigned char **key, size_t *keysize);
diff --git a/lib/isc/tests/ht_test.c b/lib/isc/tests/ht_test.c
index 4235b8a71b..07f338a0a4 100644
--- a/lib/isc/tests/ht_test.c
+++ b/lib/isc/tests/ht_test.c
@@ -203,11 +203,9 @@ test_ht_iterator() {
 	isc_mem_t *mctx = NULL;
 	isc_ht_iter_t * iter = NULL;
 	uintptr_t i;
-	void *v;
 	uintptr_t count = 10000;
 	uint32_t walked;
 	unsigned char key[16];
-	unsigned char *tkey;
 	size_t tksize;
 
 	result = isc_mem_createx(0, 0, default_memalloc, default_memfree,
@@ -236,6 +234,9 @@ test_ht_iterator() {
 	     result == ISC_R_SUCCESS;
 	     result = isc_ht_iter_next(iter))
 	{
+		unsigned char *tkey = NULL;
+		void *v = NULL;
+
 		isc_ht_iter_current(iter, &v);
 		isc_ht_iter_currentkey(iter, &tkey, &tksize);
 		assert_int_equal(tksize, 16);
@@ -252,6 +253,9 @@ test_ht_iterator() {
 	walked = 0;
 	result = isc_ht_iter_first(iter);
 	while (result == ISC_R_SUCCESS) {
+		unsigned char *tkey = NULL;
+		void *v = NULL;
+
 		isc_ht_iter_current(iter, &v);
 		isc_ht_iter_currentkey(iter, &tkey, &tksize);
 		assert_int_equal(tksize, 16);
@@ -273,6 +277,9 @@ test_ht_iterator() {
 	walked = 0;
 	result = isc_ht_iter_first(iter);
 	while (result == ISC_R_SUCCESS) {
+		unsigned char *tkey = NULL;
+		void *v = NULL;
+
 		isc_ht_iter_current(iter, &v);
 		isc_ht_iter_currentkey(iter, &tkey, &tksize);
 		assert_int_equal(tksize, 16);