Textual languages

The two text-based PLC languages of IEC 61131-3:

Structured Text (ST)

Pascal-like, statement-oriented, strongly typed. Default language for new POUs in ForgeIEC. The deepest sub-tree in this reference because it is the day-to-day language and carries the highest volume of LLM-actionable diagnostics.

Instruction List (IL)

Assembly-like, accumulator-oriented. Deprecated in IEC 61131-3 third edition (2013), but matiec still accepts it and a small number of legacy POUs in older projects use it. Documented here for round-trip integrity. (Stub.)