As is common in many industries, Microsoft customer service records employ abbreviations for many commonly-used words. In the travel industry, for example, pax is used as an abbreviation for passenger. The term appears to have spread to the hotel industry, even though people who stay at a hotel aren't technically passengers. (Well, unless you think that with the outrageous prices charged by the hotels, the people are being taken for a ride.)
For a time, the standard abbreviation for customer in Microsoft's customer service records was cu. This changed, however, when it was pointed out to the people in charge of such things that cu is a swear word in Portuguese. The standard abbreviation was therefore changed to cx.
If you're reading through old customer records and you know Portuguese and you see the word cu, please understand that we are not calling the customer a rude name.
The person who introduced me to this abbreviation added, "I just spell out the word. It's not that much more work, and it's a lot easier to read."
Some years ago, I was asked to review a technical book, and one of the items of feedback I returned was that the comments in the code fragments were full of mysterious abbreviations. "Sgnl evt before lv cs." I suggested that the words be spelled out or, if you really want to use abbreviations, at least have somewhere in the text where the abbreviations are explained.
If I had wanted to demonstrate the social skills of a thermonuclear device, my feedback might have read "unls wrtg pzl bk, avd unxplnd n unnec abbvs."