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