Colomban, Thanks for the link. That's _almost exactly_ what I wanted. 

I tested using PHP file type. The only problem is I'm getting suggestions from the entire PHP tag space. 
I see this is default Geany behavior.

Can I make up my own filetype? 
Or is the best I can do just pick something that doesn't clash with the programming languages I am using, and with the auto-loading tags?

Chris