Please don't use it as an adjective. This is used too often as a synonym for destroy. However, it means something more, particularly because of its historical background. Tends to lead to weak, inactive sentences. HTML is a markup language, not a programming language.
Markup languages talk about appearance or roles.
I dislike this word for a number of reasons. One is that it is often too vague. Yes, there are others. In this case, both adjectives independently modify the noun. Obviously, for some cases, standards or custom allow you to violate these rules.