Hans,
many thanks for having added the alternate descriptions functionality to
ConTeXt.
I attach the patch, since the entry reads /AltText instead of /Alt.
At least, /Alt is the right value in PDF-1.7
(https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008…)
I cannot check PDF-2.0, but it would be weird to break
backward-compatibility here.
Many thanks for your help,
Pablo
