XCB-TRL is mainly a Xlib-like write of the XCB protocol bindings, some parts have been lightly documented. This was primarily a personal project.
See above, but its essentially a wrapper around the XCB Protocol, that provides (mostly) feature complete of the default protocol (extension support is limited.)
For example if we had XSync(display, false) it would simply be rewritten as XCBSync(display), with XCBSyncf(display) being XSync(display, true)
But thats a edge case, most are clear cut copy and paste from Xlib while still including XCB's cookie_get, reply_get stuff.