Variables & Conditional Build Tags

I assume RH's variables are just like the tables I create in MS Access. I have 5 tool platforms for which I have one help project and use cond'l build tags to differentiate the output CHMs. There are many shared commands and signals and some that are specific to each platform. These are currently presented in tables. Applying a cond'l build tag to a row in the table only leaves a blank row in teh output; it doesn't eliminate that row altogether. Can I attach a build tag to these specific commands and signals? I'd like to do this to then create "clean", coherent tables that supply just the specified build tag info.