JTBW_InsertRebarCallout command inserts a new callout to your drawing. Then, it switches to Edit Rebar Callouts window.

JTBW_EditRebarCallout command ask you to select callout(s). Then the Edit Rebar Callouts window brings up showing all properties of the rebar callouts and the shape's dimension formulas as well.

Like the Properties Panel of AutoCAD, Edit Rebar Callouts window can show properties of many callouts at once. Different values of a property will show "*VARIES*".

You can easily change Barlist, Multiplier, Block Scale of many callouts via this multi editing feature.

Because rebar callout is a dynamic block, if you edit callout via AutoCAD native commands, the new text won't fit to the leader's landing. Only via using JTBW_EditRebarCallout command, the text will fit.

You can go here to find all details of the Rebar Callout Block