This came up on the mailing list. yyyy-mm-dd (ISO 8601) is the internationally accepted format for numeric dates. This commit changes all BIPs to use that instead of dd-mm-yyyy. It also updates BIP 0001 to prescribe the new format.
Clarified that the 4-byte checksum is from double SHA256 rounds
https://en.bitcoin.it/w/index.php?title=BIP_0013&oldid=35307