Is this wording that appears in the legend of the "Chart Supplement"
re "airspace" actually used in any entry in the Chart Supplement?
No, it isn't. I would have noticed it by now, have been looking through the Chart Supplements a lot lately. Have checked multiple airports where this language ought to appear in the AIRSPACE entry in the Chart Supplement. Examples:
Chart Supplement for Northeast region, effective beginning January 27 2022:
p.32
BRIDGEPORT
IGOR I SIKORSKY MEML (BDR)(KBDR)
AIRSPACE: CLASS D svc 1130–0300Z‡; other times CLASS G.
p.34
DANBURY MUNI (DXR)(KDXR)
AIRSPACE: CLASS D svc 1200–0300Z‡; other times CLASS G.
p.36
GROTON (NEW LONDON)
GROTON–NEW LONDON (GON)(KGON
AIRSPACE: CLASS D svc 1200–0300Z‡; other times CLASS G.
p. 37
HARTFORD–BRAINARD (HFD)(KHFD)
AIRSPACE: CLASS D svc 1100–0500Z‡; other times CLASS G.
Note the lack of any reference to the floor of the overlying Class E airspace that would be in effect when the Class D airspace is closed.
Re the suggestion "Does the legend refer to a new change in notation that has simply not been implemented yet?" -- that seems extremely unlikely, as this language has been implemented in the Chart Supplement LEGEND, but not in any of the actual AIRSPACE entries in the Chart Supplement text, for nearly a year now since this question was originally posted, and possibly for much longer.
Re the suggestion "Or is it a holdover from an older notation format that has since been simplified?" -- that just doesn't make sense and is undoubtedly not the case. There's no reason this useful information would be deleted from the AIRSPACE entries in the Chart Supplement-- it doesn't take up that much extra room.
It would make sense that this content might be shortened on the corresponding airspace labels on the actual sectional charts, where there's obviously a high priority on reducing clutter, but I've seen a lot of sectional charts published over quite a few years and am certain that this language (in the longer form) never appeared there. (No implication is intended that there's any actual requirement that the phrasing of the AIRSPACE descriptions in the Chart Supplement should exactly match the corresponding labels for part-time surface-level controlled airspace on the actual sectional charts.)
So, this language appears to reflect content that was planned or considered at one time for the Chart Supplement, but never yet actually implemented. If adopted, this convention would be a useful supplement to the airspace labels on the sectional charts themselves, which say nothing about the overlying airspace. In some cases it might be easier for a pilot to obtain this information by checking the AIRSPACE descriptions in the Chart Supplement (if they had been revised to the longer form description), than by checking the sectional chart itself for nearby magenta or blue vignetting. That's what the Chart Supplement is intended to do-- to provide useful supplemental information.
And even if it is felt that this information is already adequately obtainable from the chart itself, at least the Chart Supplement LEGEND ought to match the actual AIRSPACE entries in the Chart Supplement.
Have submitted a suggestion for correction to either the Chart Supplement LEGEND, or the Chart Supplement AIRSPACE entries, via the on-line portal for such things.
