Question regarding the shape of રુ (ru) in Gujarati fonts

[vizzmay]

So I created this issue on Google Fonts back in September, but it is relevant here as well. (Caution: This is a long post.)

• Noto Sans Gujarati, version 2.001
• Noto Serif Gujarati, version 2.001

Note: Relevent letter combinations

• ર = Gujarati Ra (u+0ab0)
  • રુ = ર + ુ (u+0ac1) (Gujarati vowel sign U)
  • રૂ = ર + ૂ (u+0ac2) (Gujarati vowel sign Uu)
• र = Devanagari Ra (u+0930) (only for comparison)
  • रु = र + ु (u+0941) (Devanagari vowel sign U)
  • रू = र + ू (u+0942) (Devanagari vowel sign Uu)

In both Sans and Serif Gujarati, the letter combination રુ (ru = ર + ુ) is rendered as a ligature where the u-matra is connected to the right side of the letter. This is similar to रु in Devanagari. However, as far as I remember, Gujarati ru is written normally with the u-matra below the letter, ર‌ુ. This is consistent with Gujarati rū (રૂ) which was probably derived from ર‍ૂ.

(I’m using ZWJ to break the ligatures here. Almost all default Gujarati fonts have the ligature, so you’ll see a difference between રુ and ર‌ુ.)

I’ve gone back and checked a few examples for both cases. I found instances of રુ ligature in Saarth Jodanikosh which is a thesaurus and spelling reference book from 1949.

I have found some modern publications using this style. Nirmala UI (Microsoft’s default Indic font), Arial Unicode MS, Lohit Gujarati, and all Gujarati fonts on Google Fonts use this style. However, Shruti (MS default in older versions) uses the below-base style. (Note that Nirmala UI has copied both ligatures from Devanagari.) The last column is what a below-base style would look like in these fonts.

On the other hand, here is an example of the below-base style in a 9th standard Science textbook published by Gujarati State Board in 2014. (રુ in the word ગુરુત્વાકર્ષણ. Compare ગુરુ from Saarth Jodani Kosh above.)

A few more examples:

• Words ગુરુ and ગુરુત્વાકર્ષણ from a Guj-Guj dictionary/thesaurus (shabdkosh) published by Directorate of Language, Gujarat. (Available here along with other publications.) (From 2009)

• Examples from Kalrav, a textbook for children in 1st standard (grade) published by Gujarat State Board. (From 2015) (Available here along with other textbooks.) I have typed the same word in Noto Serif Gujarati for comparison.

• Conflicting examples from an 8th Std. Science textbook from 2020. For some inexplicable reason, તરુણાવસ્થા is the only word in this book that uses this ligature, otherwise below-base style is used.

Is there a reason why all the fonts (Google and non-Google alike) depict this letter combination like this? If this is a design decision that has stuck, can it be unstuck?

[nizarsq]

Could you include where the font came from, Font version and Character data. Thank you.