Could some1 explain "_global"

i found a photo gallery which i would like to use in my site. now the problem is that i want the gallery to load external in my main swf. as there are no _root and no _parent tags in the gallery script i believe it’s not working because of a _global tag. i never used _global so could anybody explain how to change it?

the gallery uses it like this:

_global.path = path;

btw i read the macromedia _global explanation, but couldn’t figure it out.
any help appreciated.