As we continue to work on implementing EAD (we are currently in the process of assessing whether to adopt the encoding protocol of the EAD Cookbook) we've come across a problem and I'm hoping that some of you kind and knowledgeable people can give us some advice.

In our repository we commonly assign numbers to our series and subseries. We find that this enables us to reflect the hierarchical arrangement of the materials we are describing and to express the intellectual structure of our finding aids. Indeed, with large and complex collections which may have two or more series containing subseries of similar materials, it's a very useful way of clarifying which records belong to which series. Below is an example of how we've been encoding our series/subseries titles:

Although we believe the practice of numbering series/subseries is fairly common practice in archives, we've been unable to find many examples of EAD-encoded finding aids on the web that show these numbers in their unittitles. Is it considered bad practice to include an assigned series/subseries number in the <unittitle>? I understand that, strictly speaking, "Series 1" is not, for example, part of the unittitle for records labeled "Correspondence," but since a series title is essentially a term created by the archivist anyway, how big of a tagging sin is it to add a numerical value to that term? Can anyone foresee any problems with us continuing to encode our series/subseries titles in this way, particulary in regard to sharing our finding aids down the road?