Angle irons and pads
This is a common installation where the back corners of the step sit on 6"x6"x3/8 angle irons that are bolted to the foundation. This prevents the step from settling back against the house and from getting out of level from side to side. The two front corners are centered on free floating concrete pads.
In this installation the entire step is actually suspended on large steel brackets that prevent the step from settling even if the ground under the step should settle. This option is only available on step sizes up to and including three risers.
Angle irons and posts
The back corners are installed on angle irons as described above. The front corners sit on 4' tapered pre-cast frost piers. This installation is often used when a step sits below a roof that has columns between the step and roof.
The step sits on four free floating concrete pads. This installation is generally used only in situations that are not next to a poured house foundation such as in front of a wood porch on a free standing in grade situation.