The letters PLCIO instruct the software how to manage the symbol and which catalog table to open for part number assignment and BOM details. I have for example, a PLCIO_1794IR8 Flex I/O module that inserts all at once with a fixed wire spacing, per my customer's requirement. I have made many modules over the years for customers who wanted a unique look and did not want to use the parametrically-built symbols. You can add the underscore to denote the unique identifier but it will actually function without it.
The software is very much driven by filenames (a.k.a.
The same as with terminals and connectors, there is a different syntax for PLC modules. PLC modules are not named like other symbols.
