clarify OC_REQUEST_HISTORY_SIZE
@@ -85,6 +85,11 @@ extern bool oc_ri_invoke_coap_entity_handler(void *request, void *response,
#endif /* !OC_BLOCK_WISE */
#ifdef OC_REQUEST_HISTORY
+// The size of the array used to deduplicate CoAP messages.
+// A value of 25 means that the message ID & device counter
+// are compared to the ones in the last 25 messages. If a
+// match is found, the message is dropped as it must be
+// a duplicate.
#define OC_REQUEST_HISTORY_SIZE (25)
static uint16_t history[OC_REQUEST_HISTORY_SIZE];
static uint8_t history_dev[OC_REQUEST_HISTORY_SIZE];
