I just read: "Also, I'm not very sure when $+() was added to mIRC, and if it's supported in 6.10 (2003)."
So, I guess you would need to do: "%A $+ %B" to claim it works in every version.
I can see someone running as old as 6.21 being that there is a password to bypass
the nag screen, but I wouldn't put it past someone running 5.91, because they think
multi-server support is evil and bloated, heh.
But out of curiosity, why do people even use $+(xxx,yyy,zzz)? A few less characters? I only use it for stitching dynamically named variables that get evaluated via $() at the same time. ie: $($+(%,MyArray.,%x,.,%y),2) instead of %MyArray. [ $+ [ %x ] $+ ] . [ $+ [ %y ] ] --- and then, sometimes I use that anyway.
All said and done, $+ is still mIRC's official concatenation operator.
I'm not using $+() also in my scripts (i.e. mIRC Korona) also.. i'm using $1 $+ %2 as Raccoon and, how it said, it really makes the code much more readable and i'm also using this as i familiarized with this. Both methods are right, but $1 $+ %2 uses a low format and is a reason to use this method, to avoid mismatches when you forget to put a comma between tokens :) Experienced scripters must know this :)
As a general principle, I avoid using $+() unless it really makes the code much more readable. In actuality, $+() creates a process or stack fork just to call a function that stitches strings together and returns an output. The stand-alone $+ method uses low level parser syntax handling. Granted, there are no high stakes speed improvements in this script, but I just use $+ instead of $+() out of practice and good form.
Also, I'm not very sure when $+() was added to mIRC, and if it's supported in 6.10 (2003).