Broken (or missing?) link to signature construction

On http://developer.mintchipchallenge.com/devguide/developing/common/mintchip-messages.html , the "Signature" field is described with "The role of the signature is to ensure … The construction of the signature is explained *here*."

However, the *here* link simply points back to the same page, with no obvious description of the signature construction algorithm.

Where can I find the signature construction algorithm?