Swql help with a filter in world maps

Hi guys

I've got a page with several world maps tiles and i'm trying to filter out specific sites to only show the ones I want on a map tile. I've read the manuals and I'm having problems with getting the syntax right. I've got a custom property setup called site where I've assigned a site code to nodes. I've been testing trying to get the custom property to filter only the sites I want to see. Eg.  Node.CustomProperties.Site = 'abc1*'

is that the right syntax? also if I wanted to add more than one site to the filter would it be a case or adding a "and" or something? Eg 'abc1' and 'abc2'

thanks