Add native Structured Text language support

Author: kaftanatiCreated Sep 5, 2026Updated Sep 5, 2026

Enhancement request

Add IEC 61131-3 Structured Text as a built-in Notepad++ language.

The language should recognize .st, .stx, and .iecst files and provide syntax highlighting for IEC keywords, types, standard functions, function blocks, comments, strings, numeric and date/time literals, and pragmas. It should also support code folding and include styles for both the default and Dark Mode Default themes.

A pull request implementing this enhancement is linked below.

Source: notepad-plus-plus/notepad-plus-plus