Gl_modem: now I get it

After spending a day or so trying to figure out how GLiNET is using openwrt to manage the modem
in my spitz I finally understand that they are using a piece of code for which there is no source or manual. That code is called gl_modem or possibly gl-modem. Can I get a manpage for that please at least? Or
maybe I just don’t know where to look? Please save me the trouble of installing strace. Thanks!

Gl-modem we don’t have open source.
Gl-modem takes some modem information back to the GUI, which you can get through the AT instruction.
The modem’s dial-up Internet access was exactly the same as openwrt, and we only modified the network configuration file through gl-modem.