# ProgIDs

The ProgIDs item in the File Types Explorer contains all of the programmatic identifiers—also known as application identifiers or tag names when they support file types—that you want to associate with your file extensions. For example, an .ext file extension could point to a extfile ProgID, and all of the .ext file-type information would be registered under extfile.

To create a ProgID, select or type in the desired ProgID file your extension's ProgID property. If you type in a new ProgID and press Enter, the ProgID appears in the ProgIDs tree, where you can modify its properties.

A file type's ProgID is an arbitrary string, but it should be unique on the target system. One ProgID naming convention is to append the word file to your extension without a dot—the .ext extension might use the ProgID extfile. Another convention is to name a file-type ProgID after the application used to open the file type, as in SampleApp.Document.