The thing is, when I tried a combination with "!" it would work like an OR it seemed. I mean, I got bookmarks that just had "slave" in the tags and unless I hallucinated, "slave!sheppard" for example also gave stories tagged "sheppard/mckay" that had neither a single "sheppard" nor a single "slave" let alone both. However if I subscribe to "slave-john" that wil also give me "slave!john" so I just stick with that. I wish they'd document the way special characters work. Maybe it's those that havespecial meaning in regular expressions or something. In my own tag I have a couple with an exclamation mark, but switched to hyphens mostly when I noticed that "!" sometimes caused trouble in searches.