KLVSyntax and LocalTag both use the xs:hexBinary XML type in the Groups Register XML. Some points to note:

• XML Registers processors should be aware that values for these properties such as 000f, 0f and 0F must all be handled and treated as the same value.
• The number of characters used to represent the value has no meaning. So, for example, it would be incorrect to think that in the KLV encoding of a Group a Local Tag necessarily has four bytes just because the Groups Register says 000f for the LocalTag property – it is necessary to refer to the value of Byte 6 of the Group UL to work out the Local Tag length (and other details) to be used in the KLV encoding.