Swiss Triplet is diferent from a standard triplet (3 notes in the space of 2 —
"1-trip-let, 2-trip-let, etc.", all singles:

'r l r' or 'l r l' (or 'r l l' or 'l r r', etc. )

A Swiss triplet is also 3 notes in the space of 2, but played with a flam in there:
flam, right tap, left tap, (or reversed: flam, left, right) -or written out as:

If you look closely, it ends up being a double stroke roll, except with the 2nd tap of one hand flaming the first tap of the other hand.
I love doing these - especially on double bass!!!