According to Marius Gedminas:
@samp{SetLength} is a Borland Delphi 1.0 extension.
AFAIK this function was introduced in Borland Delphi 2.0 to provide a compatible way to assign string length for various string types. Delphi 1.0 had only one string type (Borland Pascal style short strings) and didn't have such function.
Okay, I corrected it to "a Borland Delphi 2.0 extension" (until further notice;-). Thanks.
Peter