I want to develop a new format for a specialized data type. I modeled the format closely on PNG. PNG is unusual for the FourCC family in that each block ends with a checksum. In theory this can be used to check for corrupted data.
Is that checksum useful for practical cases? New formats, like Google's WebP (based on RIFF), don't have a checksum. I can't find guidelines on what to do with it, including:
- should all readers verify the checksum, or do most readers ignore it?
- what should a reader do if it's wrong?
Since I'm not convinced it's useful, and supporting the checksum makes things more complicated, I'm going to omit the checksum in the next revision. But since it's in PNG, I figure there's a good reason, I wanted to get some feedback about how people actually use that field and its relative importance.