It’s an OpenType question. Once I use IgnoreMarks in one of the lookups, it seems to remain in effect in all the lookups thereafter within the feature. But I may want to use mark in a context in subsequent look-ups. Is there a way to make it mark-aware again?
You can set lookupflag 0;
Thanks, it works! Is that the flag 0 was intended? I’m using that for a totally different purpose in another file (as explained in the Adobe spec).
I have related question. I am working on an IPA extension. I want to contextually shift breveinverteddoublecomb based on height of glyphs under it and it works well:
lookup breve {
pos n breveinverteddoublecomb’ n ringcomb <0 0 0 -120>;
} breve;
Unfortunately I have to include all possible combinations of combining accents below and above letters unless there is a smarter way. In the above example, I would love to skip or ignore @BottomAccents. Is it possible? And is it possible in selected lookups only?
Thanks.
Put the above marks in a class @aboveMarks and letters in @letters, then you’ll need a lookupflag:
lookup breve {
Lookupflag UseMarkFilteringSet @aboveMarks;
pos @abovemarks breveinverteddoublecomb' <0 0 0 120>;
pos breveinverteddoublecomb’ @letters @abovemarks <0 0 0 120>;
} breve;
I don’t think there’s a way to combine both lines into a single rule.
Don’t forget to reset the lookupflag with lookupflag 0 otherwise everything subsequent will also ignore below marks.
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Ben, thanks a lot! Just one question, how do I reset the lookupflag? At the beginning of the next lookup?
lookup brevebelow {
Lookupflag 0;
Lookupflag UseMarkFilteringSet @belowMarks;
...Yes, that would work.
I was also wondering if Lookupflag IgnoreBases would avoid the need for the class @letters, but depending on what feature this is in, this might have the unintended consequence of applying the positioning rules even when the above marks are on a different word entirely. Different features apply to different kinds of segments.
@Bendy Ben, I did test the code you sent me. Unfortunately, it does not work. The
Lookupflag UseMarkFilteringSet @aboveMarks;
just completely kills the functionality. Couldn’t be a bug in Glyphs? Or InDesign?
You might need to activate the World Ready Composer in Indesign.
I can’t use Lookupflag IgnoreBases, there are IPA letters with ascenders and accents above, descenders and two accents below, so I have to separate the letters into groups according to their height.
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In which feature did you try it? Try another one until it works 
Or is it <0 120 0 0>?
calt
It is either <0 120 0 0> or <0 0 0 -120> both options work.
I did spent several hours with lookupflags but I am afraid it just does not work. Worldready composer did not help neither.
@GeorgSeifert Georg, is the lookupflag UseMarkFilteringSet properly implemented?
In what category and subcategory is the BreveInvertedDoubleComb? If it’s set as a mark we may not be able to access it with GPOS rules this way. (Also maybe it needs to also be in the @aboveMarks class?)
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Yes! 
THANKS. I didn’t realize I have to include BreveInvertedDoubleComb in the filter or change the category. It works!!!
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Excellent! 
Those categories are often a good place to look when things don’t work.