environment variables

In ksh HISTTIMEFORMAT has no effect at all. Here is the difference between environment variables related to history:

Code:
	/bin/ksh	/bin/bash
			HISTCONTROL
	HISTCMD	
        HISTEDIT
        HISTFILE	HISTFILE
        HISTSIZE        HISTSIZE
                        HISTFILESIZE
			HISTIGNORE
			HISTTIMEFORMAT