Many places in RexxUtil documentation, it says that the return code is really a "System error code", and documents what a few of the most common values mean. Please add links to OS-specific references where each OS documents its "system error codes".
In addition, the discussion of system error codes should also mention using SysGetErrortext().
Windows system error codes may be looked up at
Here is a very rough list of things affected in RexxUtil.
I did not search the rest of the doc, so there may be things outside of RexxUtil which need similar links.
Some things in RexxUtil which belong on this list may have been missed (please add them).
Some things on this list might not really belong there (I often had to guess whether the return code looked like a "system error code" or not). Please verify that these functions really are returning system error codes.
SysSaveRexxMacroSpace (says it's the RexxSaveMacroSpace RC, but I didn't see where that's documented, either)
SysSwitchSession (says it returns GetLastError of SetForegroundWindow, but that's not documented)
SysWaitNamedPipe (WaitNamedPipe return code?)