Here is a list of all documented namespace enum values with links to the namespaces they belong to:

op_close : discord_ipc_cpp::ipc_types
op_frame : discord_ipc_cpp::ipc_types
op_handshake : discord_ipc_cpp::ipc_types
op_ping : discord_ipc_cpp::ipc_types
op_pong : discord_ipc_cpp::ipc_types