LaTeX.org

thanks.
looks like xr package only allows referencing from external files.

I think method using \input{..} would do the trick.

thanks!
i'm not sure though how to use a newcommand in file model2.tex that was defined in model1.tex?

basically, we have a bunch of tex files describing various math models.
most of the time a model is an extension of an already existing one for which there is already a tex file with description. so, the equations describing a new model are equation from the old one + some extra stuff.

instead of ...