The structure of a <Default> element is shown in the following diagram:
diagram
attributes
Name
Type
Use
Default
Fixed
Annotation
Extension
ST_Extension
required
A part name extension. A Default element matches any part whose name ends with a period followed by the value of this attribute. The package implementer shall require a non-empty extension in a Default element. [M2.6]
ContentType
ST_ContentType
required
A content type as defined in RFC 2616. Indicates the content type of any matching parts (unless overridden). The package implementer shall require a content type in a Default element and the format designer shall specify the content type. [M2.6]
annotation
Defines default mappings from the extensions of part names to content types.