What does Airspace 24 mean in this chart supplement? I found this line in Leesburg Executive Airport (KJYO)'s chart supplement:

I have looked in the Chart Supplement Legend under section 29 and there is no information about such an airspace. At the bottom of the legend it says to look at AIM's Chapter 3 for more details, but none can be found there. I googled this to no avail.
I am guessing that whatever it is might have something to do with KJYO's situation. It is located in the DC SFRA and has an FDC NOTAM &quot;Leesburg Maneuvering Area&quot; which lists required procedures when operating in and out of the airport. Don't know how &quot;24&quot; comes from all that, though.
It looks like a mistake of some kind. The next release of the Chart Supplement is valid from 2021-04-22 and the airspace line has been removed completely from the KJYO entry.