checksum

Identifies a specific revision of the $LATEST version.

When you create a new bot alias, leave the checksum field blank. If you specify a checksum you get a BadRequestException exception.

When you want to update a bot alias, set the checksum field to the checksum of the most recent revision of the $LATEST version. If you don't specify the checksum field, or if the checksum does not match the $LATEST version, you get a PreconditionFailedException exception.