def build(self, builder):
        """Build XML by appending to builder"""
        params = {}
        if self.study_oid:
            params.update(dict(StudyOID=self.study_oid))
        builder.start("AdminData", params)
        for user in self.users:
            user.build(builder)
        for location in self.locations:
            location.build(builder)

        builder.end("AdminData")