This should be ArgumentAssignmentList, with an "n".

<element name="RelativeTimeAgumentType" type="xtce:RelativeTimeArgumentType">
RelativeTimeAgumentType should have an "r" in it.

Items that previously were typed as FixedIntegerValueType but were changed to become long need to be revisited to update the documentation annotation. For instance IntegerDataType initialValue attribute documentation:
"Default/Initial value is always given in calibrated form. Default is base 10 form; binary, octal, or hexadecimal values may be given by preceding value with 0[b|B], 0[o|O|, 0[x|X] respectively."
Such forms no longer validate against the schema.

For instance the documentation for the the ArgumentIntegerDataType says that it is identical to the IntegerDataType. However the initialValue attribute is types as a FixedIntegerValueType whereas the initialValue attribute for the IntegerDataType is typed as long.

The InputSetType has a InputParameterInstanceRefType as well as a ConstantType.
The ArguementInputSetType has a InputParameterInstanceRefType as well as a InputArgumentInstanceRefType.
The inconsistency causes some confusion as to usage.