Obsolete features - LC Issue 40

In HTML 4, the obsolete is defined as:
Obsolete
An obsolete element or attribute is one for which there is no guarantee of 
support by a user agent. Obsolete elements are no longer defined in the 
specification, but are listed for historical purposes in the changes 
section of the reference manual.

HTML 4, defines deprecated as:
Deprecated
A deprecated element or attribute is one that has been outdated by newer 
constructs. Deprecated elements are defined in the reference manual in 
appropriate locations, but are clearly marked as deprecated. Deprecated 
elements may become obsolete in future versions of HTML.

These definitions are consistent with the SpecGL explanation and definition 
of deprecated.  To satisfy LC Issue 40, I propose the following:

1.  Modify the 2nd sentence of G7, as follows:
"Deprecated features should not be used and may be removed in some future 
version, at which time the feature becomes obsolete". (and link to the 
definition of obsolete)

2. Add a definition of obsolete:
"Obsolete
A deprecated feature that is no longer defined in the specification and has 
been removed from the specification."

3.  Add a checkpoint to address obsolete:
CP 7.6 Identify each obsolete feature [P3]
Conformance Requirement:  the specification MUST document each obsolete 
feature.  It is not applicable if there is no obsolete features.

Explanation:  Obsolete features are listed for historical purposes.  There 
is no guarantee of support for obsolete features by implementations of the 
specification.

ExTech: obsolete features can be listed in the change section of the 
specification (HTML 4.1)