wrote:

I'm pretty sure I mentioned PK's in my 3-part epistle 'Riveting 101,'
which I've uploaded to my blog ( bobhooversblog.blogspot.com )

-R.S.Hoover

A 'riveting' discussion, I'm sure - Mike (off to the blog)

PS - An A&P gave me a sample of a #4 sheetmetal screw which met the
Type 'A' description I initially described, but called it a "PK" screw.
I guess it's a case where a trademark name has overrun any subtilities.