Specifically, mIRC can't differentiate between the following scripts:
on ^*:TEXT:*:#:echo 4 -t # $nick says $1- | haltdef
And:
on ^*:TEXT:*:#:echo # <ctrl+k>4 $+ $timestamp $nick says $1- | haltdef
(<ctrl+k> and <ctrl+o> are the control codes)
Both of these scripts will log as the following:
<ctrl+k>4[00:00] foo says hello <ctrl+o> world