Operating /A from an alternative address

I’ve been a Radio Amateur since 1991 and I must have been asleep for much of that time. I’m sure I’ve read my BR68 (the rules and regulations of being a Radio Amateur) several times but I don’t ever recall those latter documents referring to operating from an alternative address using the ‘/a’ suffix.

The reason I raise this is because I’ve finally got my on-line license printed off and, as I usually do, read it from cover to cover. And there, bold as brass were two mentions to operating from an alternative address. I discussed this with a good friend of mine and he remembers it being in the BR68 during the seventies and eighties but thought it had been scrapped during the nineties some time.

Well any of you out there able to put us right and tell us when operating ‘/a’ was reintroduced, or whether it did, in fact, ever go away we’d be really grateful.