Thanks guys. I've now figured out the approach needed in GC. In general coding, I calculate the variables I need to produce a result and then use them to display the result. In GC, I see that things are different and the calculation of the variables is done within the function for the features you want to create. Some variables calculated within a feature are needed for other features so for the moment, I am storing them in a text feature which I can then access.
Thanks for the help.