+/** Universal unique identity size. */
+#define UUID_IDENTITY_SIZE (128/8)
+
+/** Resource Directory */
+
+/** Resource Directory URI used to Discover RD and Publish resources.*/
+#define OC_RSRVD_RD_URI "/oic/rd"
+
+/** To represent resource type with rd.*/
+#define OC_RSRVD_RESOURCE_TYPE_RD "oic.wk.rd"
+
+/** RD Discovery bias factor type. */
+#define OC_RSRVD_RD_DISCOVERY_SEL "sel"
+
+/** Base URI. */
+#define OC_RSRVD_BASE_URI "baseURI"
+
+/** Unique value per collection/link. */
+#define OC_RSRVD_INS "ins"
+
+/** Allowable resource types in the links. */
+#define OC_RSRVD_RTS "rts"
+
+/** Default relationship. */
+#define OC_RSRVD_DREL "drel"
+
+/** Defines relationship between links. */
+#define OC_RSRVD_REL "rel"
+
+/** Defines title. */
+#define OC_RSRVD_TITLE "title"
+
+/** Defines URI. */
+#define OC_RSRVD_URI "uri"
+
+/** Defines media type. */
+#define OC_RSRVD_MEDIA_TYPE "mt"
+
+/** To represent resource type with Publish RD.*/
+#define OC_RSRVD_RESOURCE_TYPE_RDPUBLISH "oic.wk.rdpub"
+
+/**
+ * Mark a parameter as unused. Used to prevent unused variable compiler warnings.
+ * Used in three cases:
+ * 1. in callbacks when one of the parameters are unused
+ * 2. when due to code changes a functions parameter is no longer
+ * used but must be left in place for backward compatibility
+ * reasons.
+ * 3. a variable is only used in the debug build variant and would
+ * give a build warning in release mode.
+ */
+#define OC_UNUSED(x) (void)(x)
+