Target: SCA Policy FW spec V1.1 (cd02-rev7)

Description:
As background, policySets can be attached either directly to SCDL
elements of using External Attachment on SCDL elements selected
by the XPath in the attachTo attribute. The following paragraph
discusses the interaction between these two attachment mechanisms.

"SCA runtimes MUST support at least one of the Direct Attachment and
External Attachment mechanisms for policySet attachment. [POL40010
<#POL40010>] SCA implementations supporting only the External Attachment
mechanism MUST ignore the policySets that are applicable via the Direct
Attachment mechanism. POL40011 <#POL40011> SCA implementations
supporting only the Direct Attachment mechanism MUST ignore the
policySets that are applicable via the External Attachment mechanism.
POL40012 <#POL40012> SCA implementations supporting both Direct
Attachment and External Attachment mechanisms MUST ignore policySets
applicable to any given SCA element via the Direct Attachment mechanism
when there exist policySets applicable to the same SCA element via the
External Attachment mechanism POL40001 <#POL40001>."

The two ideas that came up were:

1. If both Direct Attachment and External Attachment are used, the
policySets attached by these two mechanisms are unioned together.
Mike pointed out that this removes that capability of overriding Directly
attached policySets by EXtrenally attached policySets.

2. Remove the Direct Attachment mechanism for policySets.

Some may feel that it is a bit late in the spec cycle to be making such
fundamental changes but let's have a discussion and decide what we want to do.