Changes to the grammar
- the_ functions (-gen-debug)
- R-grammar (-gen-gram)

When generating a pgf 
> gf -make X.gf

one can use the additional flags (optionally)

> gf -make -gen-debug -gen-gram X.gf

If one used -gen-gram, two new files will be generated - XComp.gf and XCompConc.gf which are the R-grammar. 
One can debug them without any extra flag

> gf -make XCompConc.gf