How to check if an attribute exists in a XML file using XSL

Question

At runtime I can have two formats of a XML file:

Answer 1

     //some processing here using graph[1]/@color values

I'm going to make a guess here since your question is missing a lot of important information, such as the context in which thie appears. If your comment is correct, what you want to do is process graph[1]/xaxis and .../yaxis, not graph[1]/@color values.