This sentence assumes there is an ordered relation for UIDs, which can be true for a particular implementation, but is not the case in general as UIDs are derived from a string datatype. This kind of assumption can not be left as is without a conformance statement making mandatory the usage of a particular datatype / order relation for the UIDs. Unless implementations will never interop (even using the same datatype let say numbers hold in a string datatype: One could sort alpha, the other could cast to Int then sort numerically or vice-versa).

Also applies to Line 297