To Configure Part Selection

1. Click Options.
2. In the Options dialog box, click the MEP Layout Rules tab.
3. Under Part Selection, select the sizing option you want to specify:

   If you want to…	Then…
   allow only standard sizes from the part catalog	select Use Catalog Parts Only.
   be prompted before choosing a custom size for a part	select Prompt when Non-Standard Parts are Needed. If you accept the proposed part, the custom part is created. If you decline, the last segment drawn is removed.
   always allow custom sizes for parts	select Use Non-Standard Parts.