Have a look at
Layout > Document > (Document Setting) > Layout > Separation > Skip
in LyX 1.3.X
There is really no defskip. I'm using Ruurds LyXWin 1.3.5-nc. I have the choice between Small-, Med-, Bigskip, and Length.
Right. And whatever you choose in the document setting dialog becomes "defskip". I.e. either smallskip, medskip or bigskip becomes the default skip for the entire document.
I guess the term "defskip" suggest that this is just another LaTeX term like smallskip, etc. This, however, is not true.
I hope this helps.
Have a nice day, Michael
