ksh incompatabilities with sh?

[Ron Natalie]

At one point KSH had different syntax for things like shell functions
and the like as KSH was based on the System V release of the shell, when
those functions were unavailable in the shell.  The shell in VR2 had these
functions, but slightly different.   I believe most of this was resolved
when the legally available version of ksh came out.  If you have a non-
compatible one you are either an AT&T employee or have a illegitimate
copy of an early release.

-Ron