I suspect it is not so much an abbreviation as a shibboleth.

Why? Both of the words are long and commonly used, at least in the IT industry in which I work. And the abbrviations are easy to remember and use. You can look them up online if you're unfamiliar with them. They've been around for at least a decade. Many outsiders see jargons or dialects as intentionally obfuscating, but for the people who use them, they are not in the least.

Ceci n'est pas un seing.