Sometimes it is the case that fake or example names will be used in place of actual names for purposes of explaining something.
I have a question about one of Mr. Tanaka's points.
As a name, "Tanaka" is not so important, it is just a filler in this case.
I noticed that sometimes instead of a name, letters can be used like A, B, C..
I have a question about one of Mr. A's points.
However, is it appropriate in Japanese to use "Aさん" here especially if "Bさん" doesn't exist? When is it appropriate to use an actual name like "田中さん" or a letter "Aさん"? Or is there not any distinction made in Japanese?
EDIT: What context best suits these naming conventions? Can "A,B,C" be used in the context of literature or is it only limited to Mathematics? In the example above why might "Tanaka" be a better fit compared to "A,B,C"?