Attribute ids must be unique within the entire collection

From DLXS Documentation

[edit] The use of IDs as attributes on elements.

I want to make it clear that we are NOT talking about the eadid here, but refer to IDs used to identify the element so that it can be referred to, or referenced from, somewhere else. You no doubt all know that each ID within a document must be unique (and the DTD enforces this). However, you may not have thought about the consequences of joining all your finding aids into one collection. Your IDs will need to be unique across the entire collection. One way to ensure this is to prefix ID values with the eadid for a given document. At this time, there is no functionality in DLXS that requires you to have IDs on any elements, but you may have used them for your own internal purposes. We have run into this ourselves and I just wanted to give everyone a heads-up, on the theory that our problems are fairly typical.

The data preparation script preparedocs.pl appends a unique number to id attributes. This may or may not be appropriate for your collection. If you use id attributes in your EADs you should look at the code for preparedocs.pl and determine if you need to make appropriate changes. For more discussion of these issues and of preparedocs.pl see [#DataPrepStep2 concatenating the files into one larger XML file]