Openings in these load bearing walls such as doors and windows were typically small and spanned by steel lintels or masonry arches.
In these buildings, brick, stone, or other masonry cladding is often just a single wythe of material called a veneer since it is non-loadbearing.
The only way to support the weight of this veneer across a wide opening is by providing a shelf angle on which the masonry bears.
Shelf angles are in reality a horizontal expansion joint which allows growth of the brick below the shelf angle and to allow movement or shrinkage of the frame without putting stresses on the brick veneer.
[2] In the United States, common sizes for steel shelf angles include L 3" x 3" x 1/4" and L 4" x 4" x 1/4".In the UK and Europe shelf angles / masonry support are predominantly manufactured in stainless steel to prevent corrosion and failure.