PreserveElements and PreserveAttributes

The <PreserveElements> and <PreserveAttributes> elements, as defined in Part 5, allow a markup language to specify the conditions under which extensions should be round-tripped, even when their contents are edited. Within the context of the markup languages explicitly defined by this Standard, no such conditions are specified, and therefore applications are not obliged to support these hints at any point in an Office Open XML document. Instead, the well-defined extensibility constructs defined below should be used.

All other constructs defined in Part 5 shall be supported.