Here's an example: If I have a quote that I wrote that says "A diamond's scratch is its character flaw. It is still beautiful to all." Does it go with the As or does it go with the Ds? I know the at the start of a statement is a descriptive so "the rose" would be put in Rs not Ts. Is A the same way? Or is it just another word?
I've never heard of the term "descriptive" as a name for such words, but "a," "an," and "the" are collectively called "articles." And yes, you treat them as if they weren't there when alphabetizing phrases. So "A diamond's" would go under "D".