I did say for "those enthusiasts who wish to use an alpha designation identify them as "DT" class ... "
So, basically you are suggesting that "enthusiasts", if they have an inclination to do so, just invent imaginary class designations for locos? Well fine - actually I have done that in my head for years, postulating scenarios along the lines of "....wouldn't it have been more logical if they did this......" - but I have never (and don't expect anyone else) to share them in conversation or on the record in a serious attempt to attribute an "identity" that has no basis in fact. However, if anyone wants to suggest / discuss possible alternative i.d.s for locos, I am happy to contibute my ideas (e.g "ZM" instead of "MKA" or "DR" (i.e. D-R(ebuilt) instead or "D" to differentiate from the unmodified original WAGR "D") - but of course, the exercise is purely academic and meaningless in the 'real world' and should be avoided in record keeping to avoid contaminating the historical record with rubbish.
As you and Steve have voted yourselves outside the group to whom the remark was directed, of course it will be meaningless to you.
Not only just me. It should be meaningless to everyone because it is meaningless, unless part of an imaginary scenario discussion as I noted above, which I do not have a problem with, as long as it is acknowledged as just a "what if" discussion.
Identification is only useful for those who have an interest, and who use a shared system.
Yes, but the usefulness quickly fades if random furphys get thrown in that have no official acceptance and the system is no longer shared.
but get a bit confused with the 21xx multi-family.
Well I get (or got) confused with the NSWGR 4XXX (esp. the 42X or 44X) family, the QR 21XX and 24XX family (esp. with oddities like the 1550's - now of course put back into the 2XXX series since rebuilding to 23XXs) and the VR "T"s (three totally different classes with the same classification - WTF?). So what? Get used to it and get over it!
But, by the same token, AIUI, Damien White spoke of "locos like the D-class"
The back reference of old redundant i.d.'s will never be banished from conversation or the record, but that isn't an issue when used in context and with acknowledgement that the letter classes are redundant. For instance, there is no such thing as DQ2001. It is 2001 - but it WAS DQ6007 and reference to DQ on its own or as DQ6007 is correct.