That is a pain. It used to work in the way that Doc suggested, where only environment variables with values got expanded.
To get over the problem in the short term, specify the percent symbols individually, or use a short function:
Code:
"String with 'LIKE' pattern match: "+udfLikeVar("TEST")+@CRLF
Function udfLikeVar($s) $udfLikeVar=Chr(37)+$s+Chr(37) EndFunction
