HTML Reference Guide
<NEXTID> ... NEXTID
The NEXTID element is included for historical reasons only and is may be generated by some older text editors. HTML documents should not contain NEXTID elements any more. The element is meant to give a hint for the NAME value to use when creating a new hyperlink element instance (A) while editing an HTML document and should be distinct from all NAME attribute values on other A elements. This element was introduced in HTML 2 but has since disappeared in later versions.
n - Identifies the value of this attribute as a unique naming system for use in creating new anchor (A) tags within the document.