Sheet metal rules describe sheet metal part characteristics and how the parts are manufactured.
A named Sheet Metal Rule (for example: Stainless steel (in) or Aluminium (in)) captures these parameters and applies them by default when you create a new sheet metal body.
There are pre-defined sheet metal rules that are stored in the sheet metal library. "In this design" lists any rules that have been selected for the active document.
Create custom rules to your specific material specifications. You can also edit, switch, delete, and override rules.