The problem was that the process separator colon (':') was also
used in drive letters (e.g. "C:\WINDOWS") and that the colon
in the drive letter was used to split the path in two (i.e.
"C" and "\WINDOWS").
To keep things simple, I changed the process separator from
':' on Windows and ';' on Unix to '#' (pound) on all systems.
The pipe separator to pipe output from one process into the
next process remains '|' (pipe).