.P21 File Extension
File TypeExpress STEP Data Model File
What is a P21 file?
3D model format used for three-dimensional product data representation and exchange; saved in an ACSII text format specified by ISO 10303-21; used primarily for industrial automation systems and integration purposes.
NOTE: Express AIM (Application Integrated Model) and MIM (Modular Integrated Model) files must use the .STP extension.