TXF Categories - USA only ?

[David J Patrick]

    Under Edit>Tax Options> there lives a clever dialog to assign tax 
categories (TFX) to accounts.
The tax forms listed (gnuCash 1.8.7) seem generic, nay, universal, but 
the final entries refer to Federal and State taxes. This must mean that 
the forms are incorrect for Canada.
    What exactly is a TFX and where do I get one that applies to me ?
thanks,
djp