Missing Value on Alphanumeric

[Marc-Olivier Z]

Morning everyone!
Please, can someone help to know how to avoid any possibility to leave an alphanumeric field empty?
I'm looking for that for a while but I do not make it

[shafique arif]

Try this.

PROC NAME

POSTPROC
if length(strip($))=0 then
errmsg("You can not leave this field blank: Please reenter");
reenter;
endif;