# in data ref/def

Hi all,

I have a question about the usage of the # in a data-ref

You can define a data element as:

<DATA-DEF name="car" structref="#vehicle"/>

If you refer to it you do it as follows:
<DATA-REF name="#car"/>

So I noticed in every example that in the DEF-part no # is used. In
the REF-part, it is always used.

Am I correct in this? Is there a 'formal' reason about this (I have to
explain it in a paper)?

Thanks!