[MPEG-OTSPEC] Rules for cubic bits in glyf flags include undefined behaviour for some configurations

[Skef Iterum]

On-curve points are addressed by a separate requirement in the same section:

    The CUBIC flag must only be used on off-curve points. It is reserved
    and must be set to zero, for on-curve points.

Skef

On 10/3/23 16:05, Bob Hallissy wrote:
>
>
> On 9/23/2023 1:02 PM, Laurence Penney wrote:
>> All the off-curve points between two on-curve points (with wrap-around) must either
>> have the CUBIC flag clear, or have the CUBIC flag set.
>
> I find the above ambiguous -- my first reaction was "well the CUBIC 
> flag is binary so of course they will all have the CUBIC flag either 
> set or clear. duh."   I realized later what (I think) was trying to be 
> said is that they must all /agree/, i.e., all set or all clear.
>
> Also the statement is ambiguous about whether it applies to arbitrary 
> pairs of on-curve points or not.
>
> Could this be worded more clearly, maybe:
> Consecutive off-curve points between two on-curve points (with wrap-around) must have the same CUBIC flag value.
> Bob
>
>
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