mongoose/docs/c-api/mg_net.h/mg_mgr_init_opt.md

title	decl_name	symbol_kind	signature
mg_mgr_init_opt()	mg_mgr_init_opt	func	void mg_mgr_init_opt(struct mg_mgr *mgr, void *user_data, struct mg_mgr_init_opts opts);

Like mg_mgr_init but with more options.

Notably, this allows you to create a manger and choose dynamically which networking interface implementation to use.