makeotf error: coverage section too large

Rainer Erich Scheichelbauer
Rainer Erich Scheichelbauer Posts: 157
in Type Design Software
What precisely does the makeotf error ‘coverage section too large’ mean?

It is followed by a hex number in parentheses, like ‘(10da6)’. Now I realize this is larger than FFFF, probably making a table too large. I have a few pretty large OT classes in the font (900+ glyphs). Would the ‘coverage’ of those classes be ‘too large’?
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  • Rainer Erich Scheichelbauer
    Rainer Erich Scheichelbauer Posts: 157
    edited October 2013
    It seems I can partially answer my own question.
    Contextual features of this sort can cause the error:

    pos @LETTER @LETTER @LETTER @LETTER @LETTER' <0 10 0 0>;

    If you have many of these lines, with many @LETTERs following each other and a relatively large class @LETTER, your coverage section can become too large.

    But, alas, this doesn’t seem to be the full story. I kept reducing the code, and the number between parentheses kept changing, but – and this is what I don’t understand – it was not always getting smaller. So, I still don’t know what a coverage section is.
  • Kent Lew
    Kent Lew Posts: 974
    FWIW, in the TTX xml representation of a Contextual LookupType, the tables for the various positions are referred to as BacktrackCoverage, InputCoverage, and LookAheadCoverage. I don’t know if AFDKO thinks in the same terms.

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