11.4 SGML Document Generator
The SGML document generator generates an SGML document or subdocument from a result grove.  The operation of the SGML document generator is specified in terms of a verification grove, which is the grove that would be built by parsing the SGML document or subdocument generated from the result grove using a grove plan that included all classes and properties of the SGML property set.

NOTE 34

An implementation is not required to build a verification grove.
A result grove is valid if it is possible to generate a conforming SGML document or subdocument from the result grove such that there is a verification mapping from the result grove to the verification grove which meets the requirements specified in section 11.4.1, Verification Mapping.  If the result grove is valid, an implementation shall generate such a document or subdocument.  An implementation shall report that a result grove is not valid if and only if the result grove is not valid.