scope:

This Recommendation - International Standard specifies a mapping from any XSD Schema into an ASN.1 schema. The ASN.1 schema supports the same semantics and validates the same set of XML documents. This Recommendation - International Standard specifies the final XER encoding instructions that are to be applied as part of the defined mapping to ASN.1 types, but does not specify which syntactic form is to be used for the specification of those final XER encoding instructions, or the order or manner of their assignment. There are different ways (syntactically) of assigning XER encoding instructions for use in EXTENDED-XER encodings (for example, use of ASN.1 type prefix encoding instructions or use of an XER encoding control section). The choice of these syntactic forms is a matter of style and is outside the scope of this Recommendation - International Standard.