In programming, the term orthogonal is used to describe two concerns or aspects of a program which are (or should be) mutually independent. For example, the task of password protecting a web page is independent from the actual business content of the page. So we might say that page security is orthogonal to page content. This might imply that individual content pages of your site shouldn't be cluttered with security code. Rather, security code should be placed in it's own module, such that changes to the security module wouldn't require every page to be updated.