Thanks for the reply.
This use of nested tables is quite specific and is the best solution to my problem based on what I know. I have some html files containing descriptions of text commands for a desktop application. Each command has a number of optional parameters and modifiers and is described using a special notation. The idea is to construct tables (or things that look like tables) to describe each command so that users can understand them more easily. A script creates each of these tables dynamically based on each command on every html page, and appends them to each page.
I'll create some code samples and post them.