Basic Versioning Packages

  Another question regarding basic versioning packages.

Section 2.1 of the spec states:

> Although a server MAY support any combination of versioning features, 
> in order to minimize the complexity of a WebDAV basic versioning 
> client, a WebDAV basic versioning server SHOULD support one of the 
> following three "packages" (feature sets):
>
> - Core-Versioning Package: version-control
>
> - Basic-Server-Workspace Package: version-control, workspace, 
> version-history, checkout
>
> - Basic-Client-Workspace Package: version-control, working-resource, 
> update, label
>

In reviewing the features, it seems to me that a combination of 
version-control and checkout-in-place would meet our needs very well and 
provide a minimalist yet complete package. Yet, the spec states that we 
SHOULD not provide this combination. I'm trying to get a feeling for 
this statement from the spec.

What is the rationale behind this restriction?

The referred spec, RFC 2119, defines SHOULD as,

>This word, or the adjective "RECOMMENDED", mean that there
>   may exist valid reasons in particular circumstances to ignore a
>   particular item, but the full implications must be understood and
>   carefully weighed before choosing a different course.
>
The full implications of ignoring this SHOULD are not at all clear to 
me. My proposed combination seems reasonable. Can someone please 
enlighten me?

Jeff Thompson