What is the meaning of "transition area" as used by the FAA? Has the meaning changed over time since the term was introduced? What is the meaning of "transition area" as used by the FAA?  Does it currently have a specific meaning?  Does the FAA still use the term at all?  Has the meaning changed over time since the term was introduced?  Is it a term that ceased to have a specific official meaning after the September 1993 "alphabet" airspace reclassification?

Additional context:

FAR 71.71 reads--


  § 71.71 Class E airspace. Class E Airspace consists of:
  
  (c) The airspace areas listed as domestic airspace areas in subpart E
  of FAA Order 7400.11D (incorporated by reference, see § 71.1) which
  extend upward from 700 feet or more above the surface of the earth
  when designated in conjunction with an airport for which an approved
  instrument approach procedure has been prescribed, or from 1,200 feet
  or more above the surface of the earth for the purpose of
  transitioning to or from the terminal or en route environment.


Does this suggest that the term "transition area" is best reserved for areas of Class E airspace with a floor at 1200' AGL?

The term "transition area" does not appear in the FAA's "Airspace Designations and Reporting Points" document, current edition Order JO 7400.11D.

As airspace with a 1200' Class E floor has proliferated to cover most of the US, it seems to have become a common practice to use the term "transition area" specifically to refer to areas with a 700' Class E floor that are protecting instrument approaches. Is this really a correct practice?
As per the FAA Procedures for Handling Airspace Matters:

Transitional areas, Class E, are designated to serve terminal and en route aircraft to include helicopter operations such as:
a. Transitioning to/from terminal and en route.
b. Transiting between airways and routes.
c. En route climbs or descents.
d. Holding.
e. Radar vectors.
f. Providing for course changes.
g. When the route under consideration is almost all within existing Class E airspace and small additions would complete the coverage.
NOTE-
The only areas that are normally excluded in the Class E description should be limited to Mexico, Canada, SUA and international airspace. Exclude SUA only when active. Do not exclude Federal Airways or other airspace areas.
h. En route training operations.

Link here.
I don't know that this definition has necessarily &quot;changed&quot;, but they apparently thought it needed clarification in 2011.