LaTeX.org

Thanks

Following on from your suggestion, I also found this which does the job:
http://www.cs.brown.edu/system/software ... doceqn.pdf

LaTeX lets you \label an equation then later \ref it.

I want to write two macros, \mylabel and \myref which do the following:

\mylabel behaves like \label if the equation is actually referred to in the document (using \myref). If not it behaves like \nonumber.

I did this a long time ago in TeX ...