If you begin using a new combination of tag-based code, but with server-side tags which are parsed (such as ASP, JSP, PHP and so on) you can define new keywords that tidy will recognise.

New Empty Tags

Use this to declare new empty inline tags. The option takes a space or comma separated list of tag names. Unless you declare new tags, Tidy will refuse to generate a tidied file if the input includes previously unknown tags.

New In-Line Tags

Use this to declare new non-empty inline tags. The option takes a space or comma separated list of tag names. Unless you declare new tags, Tidy will refuse to generate a tidied file if the input includes previously unknown tags.

New Block Level Tags

Use this to declare new block-level tags. The option takes a space or comma separated list of tag names. Unless you declare new tags, Tidy will refuse to generate a tidied file if the input includes previously unknown tags.

New Preformatted Tags

Use this to declare new tags that are to be processed in exactly the same way as HTML's pre element. The option takes a space or comma separated list of tag names. Unless you declare new tags, Tidy will refuse to generate a tidied file if the input includes previously unknown tags. Note you can't as yet add new CDATA elements (similar to script).