DocumentID: ECMA-376/Part5/9.2 Title: ECMA-376, Part5: 9.2 Alternate-Content Elements Extracted-From: ECMA-376 Office Open XML File Formats, 1st Edition / December 2006 Warning: Coverted to HTML format by a script known to have bugs
[Note: Markup producers can generate a markup document that includes multiple markup alternatives, each labeled with the namespaces that needs to be understood by any markup consumer choosing that alternative. A markup consumer shall choose only a single alternative. A particular markup alternative can exploit features introduced in subsequent revisions of the markup specification or in extensions to the markup specification.
In some cases, the Ignorable attribute could provide flexibility sufficient for a markup producer to create an acceptable experience to users of a markup consumer that is unaware of any revisions or extensions. In other cases, it could be desirable or necessary for markup producers to provide different markup alternatives, with one alternative processed by markup consumers implemented according to particular revisions or extensions of the markup specification, and others processed by markup consumers implemented according to different revisions or extensions of the markup specification. end note]