Addition of Blackboard bold (and possibly other) letters #1
Description
Blackboard bold letters should be added for those that exist in Unicode. Other letter-like symbols from the same Unicode code block should also be considered (for example, all flavors of the letter R would probably be helpful as real number notation is hardly universal).
See this link:
https://www.compart.com/en/unicode/block/U+2100
Issue discovered in trying to create a blackboard bold R (ℝ) (which can be created (where supported) by typing "211d" (without quotes), then immediately Alt-X (on Windows).