font silent substitution

[muralir77854934]

Hi,
I'm using the STIX Two Text font for the "greater than or equal to" symbol (Unicode 2265). However, in the generated PDF, it appears as a Symbol font instead.

It seems InDesign automatically substituted the f ont because STIX Two Text does not include the U+2265 character.

Since the missing glyph wasn't flagged, it's hard to identify the issue.

Is there any way to detect missing glyphs in InDesign, either manually or through a script?

Regards,

Murali

[Peter Kahrel]

Missing glyphs are shown as pink boxes. Your greater-than-or-equal-to character isn't missing, it's in the STIX font. Why InDesign changed the font during PDF export is beyond me.

[muralir77854934]

Hi Peter Kahrel, The Unicode character U+2265 (≥) does not exist in the STIX Two Text font, which causes it to be automatically substituted—often with the Symbol font—in the output PDF. You can check the attached PDF.

Regards,

Murali

[Peter Kahrel]

But in the InDesign screenshot you show that the document uses one font, and U+2265 is shown correctly. Can you select the character and open the Character panel so that you can see which font is applied to U+2265? And post a screenshot?

[muralir77854934]

I have attached screenshot

[muralir77854934]

Also attached my document.

[Peter Kahrel]

Strange, I see the same behaviour as you do. U+2265 is indeed not in Stix Two Text, so how InDesign manages to render the glyph is beyond me. And how it applies Symbol on PDF export is equally mysterious (for me at any rate).

But anyway, to return to your original question, no, you can't find such characters. 

[Dirk Becker]

Thanks for the example document.

On a sidenote:

You were originally using STIX Two Text (OTF), while my Mac 13.7.5 has STIX Two Text (OTF).

The difference is the former is OTF CFF, while the latter is OTF TT, and a variable font at that.

Back to the substituted glyph: InDesign preserves composed text to avoid reflow even across versions. This "wax" (internal name) is not accessible by scripting, but the Symbol font is showing there. Was the U+2265 available in the original OTF-CFF? I haven't checked but I doubt, after looking at the original wax from the 2020 composer.

Using a plug-in with an own, very simple composer that exercises the supported OpenType features, I can also clearly see the missing glyph. Another todo item if I ever get back to that project – figure out how InDesign decides to use Symbol, and show it the same way as with the faux Superscript.

So what would you do if you could detect such substitutions, deep within the bits and bytes of the document? Turn it into another pink overlay, or a preflight rule? Is this too esoteric, or a frequent case just missed because nobody is looking for it?

[Brad @ Roaring Mouse]

Symbol font substitution has been a thing since the beginning and the days of PageMaker. Whenever a font did not have that specific glyph in its own set (most fonts back in the day didn't), Symbol stepped in. This included standard things like the © and ™.

So what you are seeing is normal behavior. Fonts eventually started to include these glyphs and, in the case of Pagemaker, you had an option to use one or the other.

InDesign, similarly, does this automatically, and of course newer fonts have them, so the symbol substitution doesn't happen. You will also notice there are no styles to the Symbol font... e.g. there is no Bold version.

To be clear, this is separate from the Missing Glyph Protection in Preferences > Advanced Type, which is meant to substitute another font (usually InDesign's default, say Myriad) if the typeface you were using was missing a multi-part glyph like particular accented character.