The types xs:hexBinary and xs:base64Binary are currently unordered (that is, the operators le/ge/lt/gt are not defined). It is clearly possible to define an ordering for these types.

Making the types ordered is desirable for three reasons:

(a) orthogonality: it's an arbitrary restriction and we shouldn't have arbitrary restrictions.

(b) a new function collation-key() is being introduced under the maps proposal. At present this only supports equality matching, but there are obvious use cases for ordered collation keys. Collation keys are often binary (e.g. in the UCA algorithm for generating collation keys; this will generate a requirement for ordering of binary values

(c) an EXPath initiative is currently defining a library of functions for handling binary data. It is possible for such a community initiative to define new functions, but not to define new operators. The existence of such a function library will make use of the binary data types more popular, and generate a demand for doing magnitude comparisons.