HTML Reference Guide
<INS> ... </INS> INSERTED TEXT
The INS element is one of two elements used (the other being DEL) to allow revision control in HTML documents. The INS element is nestable and can be used in conjunction with the DEL element to indicate content and/or markup which has been inserted after the document's initial creation. A date stamp is used to mark when the change was made and no destructive changes are ever made to the document. This is useful in areas such as the legal profession where historical change information is important.
HTML documents containing revision annotations will contain all content and markup ever applied to the document. Browsers that can interpret the DEL and INS elements could possibly display the "current" state of the document or display all content with a common visual cues for inserted or deleted text. More advanced revision systems could allow for chronological snapshots of a document at any point in its history.
cite - Indicates the URL citing the reason for the change in the document.
datetime - Indicates the date and time when the contents were deleted. For more information on this format, see the ISO8601 document.