I have 2 questions which pretty much have nothing to do with each other...

first the html one...How do I link something in a higher directory without using the full url, ie: i'm in the /one/two directory, and i wanted to link something in the /one directory. How would i do that without having to type in the full url or is that just impossible?

second, for the php question, i think it'll probably be a fuction, but i'm getting information from a form and i want to make sure its a integer, so what can i use to make sure it is?