Specifies which part of the member the slab should use as the boundary when a member is used as a boundary for a slab. To change the options on the list, edit the Slab Boundary Reference select list in Catalog.
Inner port-face of a bounding member
Indicates that the slab stops at the inner-most plane of the bounding member.
Centerline (axis) of a bounding member
Indicates that the slab stops at the member-line axis of the bounding member. In the picture below, the beams were placed using cardinal point 8, which means the member-line axis is in the top center of the beams.
Outer port-face of a bounding member
Indicates that the slab stops at the out-most plane of the bounding member.