Type3 FontDescriptors FontName confusion

[petervwyatt]

ISO 32000-2:2020 "Table 120 — Entries common to all font descriptors" FontName is described as "(Required) The PostScript name of the font. This name shall be the same as the value of BaseFont in the font or CIDFont dictionary that refers to this font descriptor."

Type3 fonts don't have BaseName as defined by Table 110 so therefore the FontDescriptor FontName should be not required for Type3.

[lrosenthol]

Then how would you know the name of the font, such as for display in a processor's UX?

[petervwyatt]

So are you saying "Table 110 — Entries in a Type 3 font dictionary" is incorrect then and needs BaseFont?
Or that "Table 120 — Entries common to all font descriptors" FontName description is incorrect/incomplete for Type3?

[lrosenthol]

did some reading of code and here is the situation...

For Type 3 fonts, the name comes from the Name key (if present) in the Type 3 font dictionary. For all other font types, it comes from the BaseFont key of the relevant subtype's font dictionary (eg. T1, TTF, etc.).

The FontName key in the font descriptor dictionary is used primarily for the purpose of determining if a font has been subset, based on the requirements of 9.9.2 (Font subsets).

Since Type 3 fonts are either always subset or never subset (depending on how you look at it), there is never a need to have the FontName key present in the font descriptor dictionary. Accordingly, I'd change Table 120 to make it "(Required for non-Type 3 fonts)".

[petervwyatt]

Proposed solution: change Table 120 — Entries common to all font descriptors, FontName to say:

(Required for non-Type 3 fonts)

[MPBailey]

Just saying "Required for non-Type 3 fonts" doesn't say it shall not be there for Type 3, which leads to two problems:

• the rest of the text doesn't make any sense for t3 fonts
• it doesn't make any statement about it having to match anything else for a T3 font.

It may be going a bit overboard, but:

(Required for fonts other than Type 3) The PostScript name of the font. For Type 3 fonts that include a Name entry in the Type 3 font dictionary, this name shall match the value of that key. For all fonts other than Type 3 this name shall be the same as the value of BaseFont in the font or CIDFont dictionary that refers to this font descriptor.