I just found this assertion in https://en.wikipedia.org/wiki/Uniscribe:
"Microsoft worked with the Unicode Technical Committee to make shaping requirements available in a machine readable format, so a complete definition of each supported script will be included in the Unicode standard and updating or adding new scripts will be significantly simplified." It was added on 14 August 2016. Apart from the holding of discussions and the consequences for Uniscribe/DirectWrite, is this true or is someone adding two and two together and making five? 1. In particular, is this anything more than reading too much into the General_Category, Indic_syllabic_Category and Indic_Positional_Category? They could only work if the regular expressions in the documentation of the Universal Script Engine were correct (we know they aren't), and there are many shaping requirements that font developers have to discover from other sources. If there is more to it: 2. Are there "shaping requirements available in machine readable format", and if so, how can one obtain them? 3. When will these "complete definition[s] of each supporting script [...] be included in the Unicode standard"? How will they be checked? (There is a very good chance that many of them would be wrong.) Richard.