Contains abstract model for grammar-based schema and concrete verifier implementation for the abstract schema.
The model of the schema consists of two interfaces:
Note that these definitions capture schema from verifier's point of view. ���ɑ��Ē����ȃX�L�[�}�̃I�u�W�F�N�g���f���ƁA���̃A���S���Y���ɓ��������A�_�v�^�Ƃ͕ʂɗp�ӂ���̂��]�܂����BThese definitions are for the latter, not for the former.