We mean here ASCII file format (files you can read with any text editor). Exchange means that there is not too much data lost in the transfer.
How to convert a CAD file
Translating tools and Services
Unisurf
IGES
very widely used internationally
STEP
the more up to date
Standards
used in the CADCAM field.
SET
French standard or aerospace and automotive industry
PDES
used in USA