There are several formats associated with Character Cards. Each of them is completely unofficial and more consensus based than definitively declared. Each interface has subtle behavioral differences that can have surprising results. The following specifications are described here to the best of our knowledge.

• CCPNG explains how metadata is stored into a PNG, forming all (PNG) Character Cards
• CCv1 is the original, now outdated Version 1 metadata specification
• CCv2 is the ubiquitous, Version 2 metadata specification
• CCv3 is the increasingly popular, Version 3 metadata specification

While several proposed standards circulate, the only ones we've encountered are the following two:

• CCv2 Lorebook is the lorebook format specified alongside CCv2
• WorldInfo is the undocumented lorebook format used by SillyTavern