Just a note: If we make this schema more restrictive, we diverge from the original schema. - Jochen
This is explained in the beginning of section 4. Dataformat
When the IP-address is obfuscated, this will have the disadvantage that information on the geographic location, for instance, can no longer be derived. For this reason, the C-Class subnet must be provided. The C-Class subnet, which consists of the three most significant bytes from the IP-address, is used to designate the network ID. The final (most significant) byte, which designates the HOST ID, is replaced with a '0'. The C-class Subnet may optionally be hashed using MD5 encryption.
A data-URI, consisting of the prefix "data:,", followed either by a 32-digit hexadecimal number, or by three hexadecimal numbers separated by a dot, followed by a dot and a '0'.
The request type specifies if the request is for an object file or a metadata record.
One of these values must be used: