This proposal allows multiple atom:entry elements with the same atom:id value in the same Atom Feed Document.
This proposal is based on PaceAllowDuplicateIDs. The addition of atom:modified means that it is not necessary to require multiple revisions of an entry to have unique atom:updated values, because atom:modified can be used to more reliably identify the latest revision of an entry.
PaceAllowDuplicateIDs requires entries with duplicate ids in a feed to have unique values of atom:updated. This is currently necessary so that a processor can identify the latest revision of an entry. But it is not possible for a re-publisher to emit unique values of atom:updated for multiple revisions of an entry unless they drop revisions with the same date. Just because an author didnít assert that an update was subjectively significant, doesnít imply that a re-publisher or archiver will not want to emit it in a feed.
atom:updated doesnít reliably differentiate different multiple revisions of an entry; the value of atom:updated is only updated when the author wishes to indicate a significant change, but archivers and intermediaries may wish to emit all revisions of entries. Atom requires a Date construct that can be reliably used to distinguish multiple revisions of an entry and select the latest.
1. Remove the last bullet point in 4.1.1
2. Add the following paragraph, either to atom:entry or atom:feed, at the editors' discretion.
If multiple atom:entry elements with the same atom:id value appear in an Atom Feed document, they represent multiple revisions of the same entry; software MAY choose to display all of them or some subset of them. One typical behavior would be to display only the entry with the latest atom:modified timestamp.
Improves usability of Atom as a feed archive format. Enables Atom feeds to provide multiple timestamped revisions of entry descriptions.
Requires PaceDateModified2 to be accepted.
This proposal is based on draft-ietf-atompub-format-08.txt.