Introduction

Ladder diagram (LD), graphical

Function block diagram (FBD), graphical

Structured text (ST), textual

Instruction list (IL), textual (deprecated in 3rd edition of the standard[1])

Sequential function chart (SFC), has elements to organize programs for sequential and parallel control processing.

https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_plc_intro/9007199390802571.html&id=366170221893129348

https://en.wikipedia.org/wiki/IEC_61131-3

https://www.logic-control.com/datasheets/28/Compumotor/ACR/IEC61131-3 Reference.pdf