One of my favorite watercooler stories is about the origin of ISO20022 abbreviations.
ISO20022 is the XML-based format to exchange messages in inter-banking networks like SWIFT or SEPA., It replaced the old, ASN.1 inspired format. You can see both side by side here:
Notice the strange element names. Cdtr stands for Creditor, Nm for Name... for the most part, the abbreviations are easy to guess, but the obvious question is, why do they use abbreviations to start with?
Turns out, the standard first used unabbreviated element names, but once SWIFT and banks started implementing it, multiple complaints were raised about the increased traffic and storage space. The complaints bubbled up to the Standards Department and were put in a panel discussion during the yearly SWIFT conference. Where suits decided that the best way to fix the situation is to abbreviate the element names.
The rumor is, most abbreviations were penned on the spot in a way that created multiple naming clashes. That is, one can not automatically convert between abbreviated and unabbreviated XML without taking into account the context.
Anyway. The conferenced ended with the statement that the problem of message size has been solved.
And this is how we landed with words like Ccy forever ingrained into the banking vocabulary.
As any tech-savvy person may guess, the best way to make the XML smaller is to compress it. At the time, there was already the XML Fast Infoset standard which, among other things, defined how to optimize the compressor vocabulary by deducing it from the XML Schema, leading to higher compression rates.