What is AT&T’s Link Editor Command Language?

The man page for ld makes reference to AT&T’s Link Editor Command Language, however a Google search does not offer a satisfactory explanation as to what AT&T’s Link Editor Command Language is or was, other than pointing to said man pages, whereas I expect a Wikipedia page coming up in the first five results. It seems like there is a vital piece of computing history missing here. Does anyone have some reference or historical documentation on this language? Something we can put in Wikipedia to preserve for posterity?