Name a few things that software developers always have strong opinions about and naming conventions on code is one of the things that surely will come up. What lengths for identifiers should we use? Should we use hungarian notation? CamelCase or under_score case? While programming guidelines covering these topics have been existing since the rise of the early programming languages, they are much less common for industrial control.
Initially the only one that I found was Beckhoffs for TwinCAT3. Most of Beckhoffs libraries and example code used this, even though even Beckhoff themselves have not been consistent. More recently PLCopen have released their coding guidelines written specifically for IEC61131-3. Just out of curiosity I decided to compare the two standards and their take on naming conventions, and comparing them to my own personal opinions.