<SEMDB> is only necessary if the dependency labeling rules in section <GRLAB> use conditions on semantic values (that is, any of tonto, semfile, synon, or asynon). Since it is needed by <GRLAB> rules, section <SEMDB> must be defined before section <GRLAB>.
The section must contain a single line specifying a configuration file for a semanticDB object. The filename may be absolute or relative to the location of the dependency rules file.
<SEMDB> ../semdb.dat </SEMDB>
The configuration file must follow the format described in section 4.2.