@@ -75,10 +75,11 @@
 {
 	OFString *_name;
 	of_dns_resource_record_class_t _recordClass;
 	of_dns_resource_record_type_t _recordType;
 	uint32_t _TTL;
+	OF_RESERVE_IVARS(4)
 }
 
 /**
  * @brief The domain name to which the resource record belongs.
  */
@@ -119,10 +120,11 @@
 /*!
  * @class OFADNSResourceRecord OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an A DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFADNSResourceRecord: OFDNSResourceRecord
 {
 	of_socket_address_t _address;
 }
 
@@ -154,10 +156,11 @@
  * @class OFAAAADNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class represenging a DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFAAAADNSResourceRecord: OFDNSResourceRecord
 {
 	of_socket_address_t _address;
 }
 
@@ -189,10 +192,11 @@
  * @class OFCNAMEDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing a CNAME DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFCNAMEDNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_alias;
 }
 
@@ -226,10 +230,11 @@
  * @class OFHINFODNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an HINFO DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFHINFODNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_CPU, *_OS;
 }
 
@@ -270,10 +275,11 @@
  * @class OFMXDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an MX DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFMXDNSResourceRecord: OFDNSResourceRecord
 {
 	uint16_t _preference;
 	OFString *_mailExchange;
 }
@@ -315,10 +321,11 @@
  * @class OFNSDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an NS DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFNSDNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_authoritativeHost;
 }
 
@@ -352,10 +359,11 @@
  * @class OFPTRDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing a PTR DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFPTRDNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_domainName;
 }
 
@@ -389,10 +397,11 @@
  * @class OFRPNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an RP DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFRPDNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_mailbox, *_TXTDomainName;
 }
 
@@ -435,10 +444,11 @@
  * @class OFSOADNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an SOA DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFSOADNSResourceRecord: OFDNSResourceRecord
 {
 	OFString *_primaryNameServer, *_responsiblePerson;
 	uint32_t _serialNumber, _refreshInterval, _retryInterval;
 	uint32_t _expirationInterval, _minTTL;
@@ -516,10 +526,11 @@
  * @class OFSRVDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing an SRV DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFSRVDNSResourceRecord: OFDNSResourceRecord
 {
 	uint16_t _priority, _weight;
 	OFString *_target;
 	uint16_t _port;
@@ -574,10 +585,11 @@
  * @class OFTXTDNSResourceRecord \
  *	  OFDNSResourceRecord.h ObjFW/OFDNSResourceRecord.h
  *
  * @brief A class representing a TXT DNS resource record.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFTXTDNSResourceRecord: OFDNSResourceRecord
 {
 	OFData *_textData;
 }