Within a WordprocessingML document, it is often necessary for specific documents to contain semantic information beyond the presentation information specified by this Office Open XML Standard. [Example: An invoice document may wish to specify that a particular sentence of text is a customer name, in order for that information to be easily extracted from the document without the need to parse the text using regular expression matching or similar. end example]

For these scenarios, multiple facilities are provided for the insertion and round-tripping of customer defined semantics within a WordprocessingML document. There are three distinct forms in which customer-defined semantics can be inserted into a WordprocessingML document, each with their own specific intended usage:

• Smart tags

• Custom XML markup

• Structured document tags (content controls)

The elements and attributes which define each of these forms is described in the following clauses.