mongoose/docs/c-api/mg_coap.h/mg_coap_add_option.md

title	decl_name	symbol_kind	signature
mg_coap_add_option()	mg_coap_add_option	func	struct mg_coap_option *mg_coap_add_option(struct mg_coap_message *cm, uint32_t number, char *value, size_t len);

Adds a new option to mg_coap_message structure. Returns pointer to the newly created option. Note: options must be freed by using mg_coap_free_options