DocumentID: ECMA-376/Part5/9.2.1 Title: ECMA-376, Part5: 9.2.1 AlternateContent Element 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
The AlternateContent element contains the full set of all possible markup alternatives. Each possible alternative is contained within either a Choice or Fallback child element of the AlternateContent element.
An AlternateContent element shall contain one or more Choice child elements, optionally followed by a Fallback child element. If present, there shall be only one Fallback element, and it shall follow all Choice elements. An AlternateContent element shall not be the child of an AlternateContent element.
More than one Choice child element might be specified, each identifying the namespaces that a markup consumer needs to understand in order to choose the markup alternative contained within the Choice element. Markup consumers shall rely solely on the namespaces identified by the Choice element rather than the alternate content markup itself in order to decide which content to use.
AlternateContent elements might include the attributes Ignorable, MustUnderstand, ProcessContent, PreserveElements, and PreserveAttributes described in this specification. These attributes' qualified names shall be prefixed when associated with an AlternateContent element. A markup consumer shall generate an error if it encounters an unprefixed attribute name associated with an AlternateContent element. [Note: A namespace declaration is not considered to be an unprefixed attribute name. end note]
AlternateContent elements might have ignored attributes or contain ignored child elements. Markup consumers shall not generate an error when encountering such attributes or child elements. However, markup consumers shall generate an error when encountering an attribute or child element of the AlternateContent element that belongs to a namespace that is neither understood nor ignorable. [Note: In addition to Choice and Fallback elements, an ignored element can occur as a child of AlternateContent. end note]
When a markup consumer processes an AlternateContent element, each successive Choice or Fallback element is considered in markup order for selection based on its attributes. If a Choice or Fallback element is not selected for processing, all of the child and descendant elements of that Choice or Fallback element shall be treated as if they did not exist. A markup consumer shall not generate an error based on any MustUnderstand attribute applied to an element contained within the content of the unselected Choice or Fallback element. A markup consumer shall not generate an error based on any markup that is contained within an unselected Choice or Fallback element, even if that markup is not conformant to this specification.
In processing an AlternateContent element, the attributes of every child Choice or Fallback element shall be processed and checked for conformance to this specification, regardless of whether the Choice or Fallback element precedes or follows the selected alternative in markup order. If the AlternateContent element's child Choice or Fallback elements include an attribute from a namespace that is not understood and is not ignorable, the markup consumer shall generate an error. Likewise, a markup consumer shall generate an error if it encounters a MustUnderstand attribute included on a Choice or Fallback element that identifies a namespace that it does not understand.
The content of the selected Choice or Fallback element is processed as though it replaces the entire AlternateContent element. All namespace declarations and compatibility-rule attributes present on the AlternateContent element or selected Choice or Fallback element shall be processed as though they appeared on every child element of the selected Choice or Fallback element. This logical removal of the parent AlternateContent, Choice, and Fallback elements shall not change the expanded name of any element or attribute contained within the selected Choice of Fallback element. Additionally, this logical removal shall not change the set of ignorable namespaces, or their corresponding preservation and content-processing behavior, when processing the contents of the selected Choice or Fallback element.
[Note: The AlternateContent element can appear as the root element of a markup document. end note]
Markup producers shall not generate AlternateContent elements that have the xml:lang or xml:space attributes. Markup consumers shall generate an error if they encounter the xml:lang or xml:space attributes on an AlternateContent element.