Try this cmd script
 ANYPARM MSG=Sample Block Mode Message

 SETVAR BML LEN ( "!MSG" )
 SETVAR ESC CHR(27)
 ECHO !ESC&j![BML]L!MSG
 PAUSE 2
 ECHO !ESC&jB

This only works for your terminal.
TELL removes the ESC char for this sequence so tell won't work.
In CSL there are several programs that do this. Check out key words
VIEW MSG or MESSAGE TELL.

You have to (on classic systems) call GENMSG (priv mode) and send the
message yourself to each terminal device. Not sure how to approach this
in Native mode (yet).

+=====================================
 Keven Miller   KC7LYD
 [log in to unmask]   (Salt Lake City, Utah, USA)
+=====================================