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Responding to Mark's original observation concerning the Tag Library  
and the EAD schema not being aligned, I pass along the following  
summary of the differences between the DTD and Schema that is straight  
from the Schema. The Tag Library was written at the same time as the  
DTD and unfortunately was not revised to reflect changes introduced in  
the Schema.

Daniel


EAD DTD / Schema Relationship
		
		With one exception (XLink elements and attributes), the EAD Schema  
is a subset of the
		EAD 2002 DTD.
		
		The Xlink compatible elements and attributes in the DTD have been  
made compliant
		by implementing XML Namespace. As a result, DTD compliant instances  
containing
		ANY of the XLink tags and attributes will not validate against the  
Schema. These instances
		must be converted into XLink compliant tags and attributes. The EAD  
Schema WG will
		provide XSLT for this conversion with the release of the official  
version of the Schema.
		
		The following elements and their XLink-specific attributes are  
impacted by this change:
		
		   arc archref
		   bibref
		   dao daogrp daoloc
		   extptr extptrloc extref extrefloc
		   linkgrp
		   ptr ptrloc
		   ref refloc resource
		   title
		
		With the exception of the XLink tags and attributes, a Schema valid  
instance will be a DTD
		valid instance. However, because of the imposition of datatype  
contrainst on specific
		attribute values, a DTD valid instance may not be Schema valid.
		
		The following attributes are impacted by the imposition of datatype  
constraints:
		
		   @normal on <unitdate> and <date>: constrained to date and date  
range subset of ISO 8601
		   @repositorycode: constrained to ISO 15511 (ISIL)
		   @mainagencycode: same as @repositorycode
		   @langcode: constrained to ISO 639-2 alpha-3 codel list
		   @scriptcode: constrained to ISO 15924 code list
		   @countrycode: constrained to ISO 3166-1 alpha-2 code list
On Apr 28, 2011, at 1:38 PM, Mark A. Matienzo wrote:

> On Thu, Apr 28, 2011 at 12:54 PM, Michele R Combs <[log in to unmask]>  
> wrote:
>> Do you by chance have a comparable list of changes that had to be  
>> made to the style sheet and/or your output processing (other than  
>> the obvious ones to accommodate the changes to the EAD) ?  For  
>> example, we use Saxon as our XSLT processor and not all versions of  
>> Saxon are schema-aware (http://www.saxonica.com/feature- 
>> matrix.html), so for us it would mean upgrading to a different  
>> version, or to something else.
>
> In my understanding, schema-aware processing really only is an issue
> if 1) you're using XSLT 2.0 and 2) you need access to schema
> information. From the XSLT 2.0 specification
> <http://www.w3.org/TR/xslt20/#stylesheets-and-schemas>:
>
> [quote]
> The conformance rules for XSLT 2.0, defined in 21 Conformance,
> distinguish between a basic XSLT processor and a schema-aware XSLT
> processor. As the names suggest, a basic XSLT processor does not
> support the features of XSLT that require access to schema
> information, either statically or dynamically. A stylesheet that works
> with a basic XSLT processor will produce the same results with a
> schema-aware XSLT processor provided that the source documents are
> untyped (that is, they are not validated against a schema). However,
> if source documents are validated against a schema then the results
> may be different from the case where they are not validated. Some
> constructs that work on untyped data may fail with typed data (for
> example, an attribute of type xs:date cannot be used as an argument of
> the substringFO function) and other constructs may produce different
> results depending on the data type (for example, given the element
> <product price="10.00" discount="2.00"/>, the expression @price gt
> @discount will return true if the attributes have type xs:decimal, but
> will return false if they are untyped.
> [/quote]
>
> It basically depends on how strongly your data is typed. If you're
> just looking to migrate from DTD-compliant to schema-compliant EAD, I
> don't think you'll have much of an issue.*
>
> * Feel free to correct me if I'm wrong.
>
> Mark A. Matienzo
> Digital Archivist, Manuscripts and Archives
> Yale University Library