Certain rules apply with regard to name length and the use of lowercase letters when specifying an identifier name:
- Name length: Open PL/I allows names up to 256 characters long.
- Lowercase names: By default, Open PL/I treats all names, including external names, as if all lowercase letters were upper case. When interfacing with non-PL/I external procedures, it may be necessary to work around this. For example, the C language preserves the case of all external names.
If Open PL/I is calling a C function or vice-versa, one of the following options is available.
- Spell with uppercase letters the external names in the C function where needed.
- Use the EXTERNAL('name') option on the PLI ENTRY declaration to specify the exact name of the external C entry point.
- Use the Open PL/I -lowercase Compiler option, which maps all external names to lower case instead of upper case. Note that all external names produced are lower case, not just the entry point to a procedure.
