Symbols for names
From Why start at x, y, z
There are many conventions to do with naming things. This page might split into several when it gets big enough.
Mathematicians tend to use single Latin letters to name things, when they can. A common consequence of this is that the author runs out of symbols, so needs to look to other alphabets or use of different typefaces to convey meaning.
Once you've exhausted all the alphabets you know, you should take a long hard look at yourself, but you might feel tempted to start using non-letter symbols.[1]