I think you're reading the print wrong or there is a slight typo (or maybe just hard to read).
The callout looks like a British pipe thread (dryseal type). This is a straight pipe thread, not a taper. The callout should be like this:
" G1/8B "
The last digit is a letter B, not an 8. That would make this thread a " 1/8-28, dryseal British pipe thread, external, class B ".
Look in a bible (Machinery's Handbook) and you can get all of the info.
Hopefully, they know what they are calling out, and not using the callout errantly. A male BSPP thread (British Standard Pipe, Parallel) will thread into a 1/8 NPT fitting (but won't seal). I've also seen many companies use this callout for American NPS threads (which is wrong - they're trying to be 'European', or shall we say 'metric').
:cheers:
It's just a part..... cutter still goes round and round....