There are a couple cases where English does not have a good rule:

"a RFLP" vs "an RFLP" - the acronym "RFLP" can be spoken by saying the letters "R" "F" "L" "P", or by pronouncing them together - "rifflip". There is no rule in English to cover this case.

When using a slash to separate words, what do you do when the terms contain more than one word? E.g. "blue tile" vs. "red tile". Should it be "blue tile/red tile"? Or "blue tile / red tile"? Or "'blue tile'/'red tile'"? There is no rule to cover this.