The AFDKO spec defines glyph range
[<firstGlyph> - <lastGlyph>]
<lastGlyph> must be the same length and can differ:
1. By a single letter from A-Z, either uppercase or lowercase.
2. By up to 3 decimal digits in a contiguous run.
Now FontForge (which doesn't use the FDK, but its own implementation) gets it right and allows ranges like uni2074-uni2079 (though not uni2074-uni207B, because that would be to much to ask of the standard... which is a failure of the standard IMHO).
But FontLab (which does use the FDK) doesn't allow such ranges, which makes me think that the FDK itself is not congruent with its own spec. Or maybe the devs were misled by the example in the spec,
[ampersand.01 - ampersand.58]
and thought that the digits needed to be a suffix separated by period? Because such glyph ranges indeed are supported in FontLab.