The following features of ksh-88 are not implemented in dbx:
set --A name for assigning values to array name
set --o particular options: -allexport bgnice gmacs markdirs noclobber nolog privileged protected viraw
typeset --l --u --L --R --H attributes
backquote (``) for command substitution (use $(...) instead)
[ [ expr ] ] compound command for expression evaluation
@(pattern[|pattern] ) extended pattern matching
co-processes (command or pipeline running in the background that communicates with your program)