Template:M summ 2002 ISDA Tax
Tax and Stamp Tax are meant to be mutually exclusive and both refer to duties levied on payments under the swap Transaction itself and not under hedges to it, so be careful when using them (especially in the context of delta-one synthetic equity swaps where the main stamp duty and capital gains issues accrue on Hedge Positions. For those you might want to introduce a conceopt like Local Taxes, or something similar.
Here’s what the ISDA Users’ guide has to say about Tax and Stamp Tax, in a footnote on page 58.