The editbox won't run commands that start with a variable/identifier. This was done a few versions ago to prevent $decode worms and the like. Unfortunately, mirc cannot distinguish between a variable assignment and a command that starts with a variable.
Using: /var = <value>
#1
//var %blah = blah | var %something = something | echo :1:1> %blah %something | %something = somethingelse | echo :1:2> %blah %something
#2
//var %blah = blah | var %something = something | echo :2> %blah %something
#3
//var %blah = blah | var %something = something | %something = somethingelse | echo :3> %blah %something
#4
//var %blah = blah | var %something = something | var %something = somethingelse | echo :4> %blah %something
would output:
#1
:1:1> blah something
#2
:2> blah something
#3 (would not output anything at all nor error of any sort)
#4
:4> blah somethingelse
therefore %var = <data> even after /var or /set, will be blocked.
but using /var %var = data *WILL* work.
i would asume it would be similar for /set
