11.3.5 SGML Prolog Parsing
(sgml-parse-prolog string)
Returns a node-list containing a single node that is the root of a grove built by parsing the prolog of an SGML document. string is the system identifier of the SGML document entity.  This is built using the default grove plan modified to exclude the instabs module.

NOTE 33

This procedure is typically used to specify the subgrove: argument to the subgrove-spec: procedure when the source and result groves have different DTDs.