It means that you can use a special character like '|' to separate the keywords in the hierarchy which will allow you to preserve the path of keywords.
ah ok,
I do not understand why this was not possible before with the komma? ( , )
The comma already separates keywords. Adding the additional separator allows something like this:
Animals | Mammal | Feline | Cat, Animals | Mammal | Canine | Dog
See the two paths? Without the path separator, the two paths would have been represented like this:
Animals, Canine, Cat, Dog, Feline, Mammal
See the difference?
-Kirk