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At the time of writing (October of 2021), InDesign does not support typesetting Avestan script: it is not recognized as a right-to-left script and therefore Avestan text is garbled when rendered in InDesign. MacOS applications that use Apple’s CoreText framework render Avestan text in the Avestan script well, but no page layout application uses CoreText. Of all page layout applications, only TeX can be tweaked to render the Avestan script correctly, which means that publications containing such Avestan-script text can and must only be typeset by TAT, who use an installation of LuaTeX. 

Web fonts

See Web Fonts and Script Proportions on Brill Websites 035 for web font, font license and font rights holder information; script and language tag and script proportion.