Secrets of the filter command?

[David Bovill]

I've always been curious about the filter command - and I am pretty sure
from examples I have seen that there is a lot more to it than is shown in
the docs.

Take this example from Jerry Daniels beautiful Galaxy:

filter someScript with "[-ofsgOFSG][-nueNUE][> ntNT]*"


What is the leading "-" doing or the "> " ???

Does anyone know what the underlying mechanism to it is - and are there any
links to a fuller documentation?