## K-Trimmed mean formula.. is it K ripley function?

On this pdf paper, authors show formulas for calculating Trimmed Mean and
Winsorized Mean on unsorted data:

http://www.jstatsoft.org/v39/c02/paper

Regarding formulas (2) , (3) and (4) ... they show that formula (4) is a way
to compute formula (2) and they use min() and max() functions practically to
solve K() on formula (2) .. BUT what is K() ?
Formula (3) is Trimmed Mean and they don't give another version of it. Should
be converted to the same form of formula (4) by using min() and max() and if
yes, how should it be written correctly?
Is K() the K-Function by Ripley? And if yes, which version?

Of course there are formulas (5) and (6) where authors give another way of computing the same Trimmed Mean on unsorted data and for which they provide their C code implementation.

However I'd like to understand how K() should be solved and written on formula (3) for Trimmed Mean which uses Winsorized Mean of formula (4).

Thanks to anyone that can explain it to me.