nextid is a parameter used by editors to generate unique
identifiers. This tag takes a single attribute which is the number
of the next document-wide numeric identifier to be allocated of
the form z123.
When modifying a document, old anchor ids should not be reused, as there may be references stored elsewhere which point to them. This is read and generated by hypertext editors. Human writers of HTML usually use mnemonic alphabetical identifiers. Browser software may ignore this tag.
nextiddoes not impact browsers in any way.