ASN.1 is easier to understand than XSD, for the XSD standard is intricate; among its complexities, you need to understand namespaces to read a schema. With ASN.1 the abstract level is clearly separated from the encoding. The pure ASN.1 Schema always results in non-ambiguous XML while when XSD is used, there are XML instances which are ambiguous. XML is very repetitive (because of it's XML syntax), so a counter-effect is that it can have more errors (but if a tool like
XMLSpy is used, this problem is reduced).