Cardfile

Cardfile (sometimes spelled CardFile or Card File) is an address book application, with a native .crd file format. It was included with Microsoft Windows 1.0 through Windows Me and Windows NT 4.

Reportedly, the Cardfile source code was included in some Windows SDKs.

There are two .crd file formats, which can be named after their signatures: "MGC" format, and the somewhat more advanced "RRG" format.

Identification
Files begin with ASCII characters " " or " ".

Sample files

 * CLIP_ART.ZIP
 * 1a_sin.crd

Links

 * Wikipedia: Cardfile
 * Windows 3.1 Card File Format, from Microsoft Support
 * The Cardwin Project
 * Freeware 64 bit CardFile replacement