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 “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.