If you need to test the compass, a small hack can be used.
Because the empty string cannot be tested, the following equation will not work:
$#CMPS#==?It does not work.:It works.$
However, it is possible to use automatic joining of text strings. Just add a letter to the text you need to test for a “null” value.
$#CMPS#a==a?It does not work.:It works.$
I hope this helps someone.