22.214.171.124 ExistRestriction Structure
RestrictType (1 byte): An unsigned integer. This value indicates the type of restriction (2) and MUST be set to 0x08.
PropTag (4 bytes): An unsigned integer. This value is the property tag of the column to be tested for existence in each row.
The ExistRestriction structure is used to guarantee meaningful results for other types of restrictions (2) that involve properties, such as property and content restrictions. The result of a restriction (2) that involves a property that does not exist on a row is undefined. By creating an AndRestriction structure that joins the property restriction with an ExistRestriction structure, a client can be guaranteed accurate results.