There are a number of "box" characters in the vicinity of U+27FB
You mean U+25FB.
U+25A1 [I think: maybe]
[and]
For diamond [...] U+25CA [I think: no]
Have you read my previous discussion and looked at UTR 25 (p. 20 and
also "Ideal Sizes" on p. 19)?
U+25AB [and] U+25FD
Definitely too small.
U+25AF (doubtful)
I've never seen the "box" as a vertical rectangle.
At http://plato.stanford.edu/entries/logic-modal/ I see that the web page
uses U+25A1 for box, and U+25CA (aka ◊ by w3c) for diamond.
Despite their quality in content, I can't regard them as normative in
typographic matters. They also use & for ∧, which is done in older books
or nowadays when an author (or copyeditor) doesn't bother.
Stephan
