github/linguist — pull request #639 by takanuva (2013-08-21 19:21:33+00:00)
Title: Added support for IEC 61131-3 languages (ST and IL)

Support for PLCs' textual programming languages as defined by IEC 61131-3, which are ST (Structured Text) and IL (Instruction List). Sadly, they don't have default file extensions, each vendor choses their own, and some even use *.txt for their code files.