What are you trying to achieve? If you want multiple entries, multiple
variables seems a logical way to go. If you want the same variable to
have a different value in different outputs, you can use variable sets:
I need a variable for specifying the type of document. The document may be Security document or Policy & Procedure document or Standards document.
While authoring a topic, i want to define which type of document it is.
From what I've seen of your post, it would appear that you will need three different variables for that. Assuming, you wish to go the variables route.
You might want to consider Snippets. They may be more suited for achieving this specific goal.
Oh, and if you only need to specify the document type when first creating it, you might also be interested in defining three different Master Pages. One for Security. One for P&P. And one for Standards. By working with Master Pages, you choose the type of document at the time you are creating it.