I don't have access to Jepp charts, but I do have access to SkyVector and this March 2012 Jepp legend.
1. On a Jeppesen IFR low enroute chart, there's occasionally a different altitude below/next to the MEA with a "T" next to it. (For example: V16 between GACEB and SHAKY, there's a "2900T" next to the 4500 MEA.) What is this "T"...
Here is a source that establishes the use of the specific phrase you mention coincident with the 'airspace redesign'. It seems to clarify the timeframe you seek but is not in the publications you specify, so I put it here separately. The document deals with charting implications of the ambiguity you describe.
The front page of the document for reference.