B - Anchor bolts or steel plates. A home's crawl space may be formed by a cripple wall (see Weak Cripple Walls page) between the foundation and the floor joists or the floor joists may rest directly on the sill plate. In either case, you should be able to see the heads of anchor bolts or steel plates installed at appropriate intervals. These fixtures fasten the sill plate to the foundation.
California Seismic Safety Commission