Schema braille to ONIX correspondance

[LaZay]

In the 2. Schema.org and ONIX section,

1. the Schema value braille can be mapped to ONIX. Code from code list 21:

• BRL = Braille edition

2. The other way around, ONIX braille type cannot be mapped onto Schema which is not accurate enough. Codes from code list 175:

• B701 = UK Uncontracted Braille
• B702 = UK Contracted Braille
• B703 = US Braille
• B704 = US Uncontracted Braille
• B705 = US Contracted Braille
• B706 = Unified English Braille

This must be pointed out so it can evolve in the future.