Definition of Values of Property Vertical_Orientation

Sławomir Osipiuk sosipiuk at
Tue Aug 23 12:12:36 CDT 2022

On Tuesday, 23 August 2022, 08:51:26 (-04:00), Asmus Freytag via Unicode 

For compatibility with older parsers, all @missing directives are wrapped 
in comments.

If @missing directives are meaningful but ignored by older parsers, doesn't 
that result in incorrect values? Is that preferable to the parser simply 
failing on a new syntax?

Would it only give incorrect values to unassigned code points?

For some properties, such as derived bidi class, the  full scheme will be 
present in 15.0, but vertical orientation missed the cutoff, so that will 
be taken care of in the next version(s).

Where multiple @missing lines are used, you will no longer see explicit 
listing of default values for reserved code points.

Then, from a parsing perspective, Vertical_Orientation is not currently 
complex (it has one default and all other values are explicit) but it will 
be complex (multiple defaults) in the next version.
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