Post Base Concrete Form
The picture above is showing you a raised
concrete base for a patio post corner, before the patio is poured.
These metal brackets are an alternative for using anchor bolts and work great in a situation like this. The holes that are drilled in the short 2 x 4 plate material will usually crack or split and provide very little support.
These metal brackets simply nail onto the 2 x 4 plates to provide the support needed to keep them from moving.