I'm new to compiling and using functions of anything other than a
relatively simple basis.  I've been reading a lot of questions and
answers on this group and am amazed at some of the complex functions
that can be built up.

I am starting to understand most of them but keep seeing "--" used in
functions - why is this used?  Does it only apply to certain functions?
I've tried typing the some of the functions posted without them
because I thought they may just have been used to clarify the structure
of the function but have noted that the end result is different with
and without the dashes.

I've tried to look up what they are and where you would use them but
I've drawn a blank so far - I know that one of you guys will be able to
help me out.

Thanks.