[DIY] polystyrene caps (was: RE: PEN, PPS caps?)

[jh]

Sorry no answer for PEN, but I have a burning question about
polystyrene caps:

Normally these are the shiny cylinder ones, with "KS" printed on them,
aren't they ? My question is are there polystyrene caps that are
labelled "KP" instead of "KS" ?? I read somewhere that "KP" would
stand for polyester, but I don't know if that's always the case.
A few years ago, I bought a large number of unsorted "polystyrene"
caps very cheap, only to find out that 90% of them were labelled
"KP". They all were these shiny cylinders, but the KS ones looked
lightly different from the KP ones, too. I was sceptical, but then again,
these were very cheap.
Now recently I bought a few expensive "polystyrenes" from Reichelt
Elektronik (great company, normally), which were also labelled "KP".
Does anybody know more about that ? It's hard to believe that they
would deliberately sell the wrong ones, but well, nobody isperfect.
Does anybody know for sure ? Can "KP" be a valid labelling for
polystyrene ??

JH.