"-0800 (GMT)" is very different from "-0800 GMT". It might seem subtle to you, but the latter is referring to -0800 in reference to GMT.
In what sphere of influence? I've never before known a time-zone initialism to mean anything other than the relevant local time zone. Nor is there generally any need to specify that the offset is UTC. (In fact ISO 8601 doesn't specify time-zone designators at all—only the offset, which is
always relative to UTC.)
(Side note: Even though UTC never differs from GMT by more than one second, the reference used for time-syncing is UTC.)
What is the point of the zzz descriptor, if it only ever yields "GMT"? One could just as easily specify that literally. Unfortunately the manual is vague about the intended output; but mIRC is the first date formatter that i've seen exhibit this behaviour.
