Importing schemas: spring-aop-2.0.xsd vs spring-aop-2.1.xsd vs spring-aop.xsd

[plethora]

When importing various spring schemas, I can choose between an increasing number of "virtual" schemaLocations.

For example, Spring 2.1M3 has the following mappings declared for the AOP namespace schemas:
http\://www.springframework.org/schema/aop/spring-aop-2.0.xsd=org/springframework/aop/config/spring-aop-2.0.xsd
http\://www.springframework.org/schema/aop/spring-aop-2.1.xsd=org/springframework/aop/config/spring-aop-2.1.xsd
http\://www.springframework.org/schema/aop/spring-aop.xsd=org/springframework/aop/config/spring-aop-2.1.xsd

The general approach seems to provide versioned "virtual" schemaLocations linking to specific versions of a schema. In addition, a "unversioned" location is defined that seems to point to the "latest" schema version.

Are there any recommendations for/against for using "versioned" or "unversioned" location variants? My own gut feeling and experience tell me that using an unversioned reference is almost a guarantee for having things break in the future. Anyone care to explain why Spring provides such unversioned location names?

[Jörg Heinicke]

I guess it avoids the need to change the versioned reference when living on the cutting edge anyway. Maybe at the very beginning it was unversioned, so it can also be a backwards compatibility reason.

Joerg