I have been taught that if you want to use an acronym or abbreviation you should write it in full the first time like this:
World Health Organisation (WHO)
But what happens if there are two or more different abbreviations which you are going to use in your text. My programming brain wants me to write the following but I am pretty sure it isn't proper English!
World Health Organisation (WHO | WHOrg)
I know my particular example is nonsense, it was just for illustrative purposes.
The actual reason I need to have multiple abbreviations is for defining mathematical symbols as well as acronyms. So an example would be:
Collision cross section (CCS, Ω)