assigned or agreed-upon
points of boundary, which are conceived to be motionless by the
individual; those
points which
demark the outermost boundaries of a
space or its corners for an
individual.
—PDC Volume 3 Approved Glossary, —PDC Volume 5 Approved Glossary, —PDC Volume 4 Approved Glossary, —PDC Volume 6 Approved Glossary, —PDC Volume 7 Approved Glossary, —PDC Volume 8 Approved Glossary, —PTS-SP Approved Glossary, —Melbourne Congress Approved Glossary (2.4.92)