hi all
i know that the folowing function opens default.asp in new window but i truly dont know wht are the folowing means:

window.open("default.asp?cat=" + menuname,"_self");

1. the "?" mark
2. ,"_self"

what the "+" usses to when it appeaars in the address line?
and how can i access for that number from other web page?

sorry for the many questions

and thanks again