Unicode slashes and backslashes
Will Robertson
I've been researching slashes and backslashes, and I've got a few
questions/problems.
Here is the list and the current control sequences I have from the
STIX table:
1. U+002F solidus <nothing>
2. U+2044 fraction slash \fracslash
3. U+2215 division slash \slash
4. U+29F8 big solidus \xsol
5. U+005C reverse solidus \backslash
6. U+2216 set minus \smallsetminus
7. U+29F5 reverse solidus operator \setminus
8. U+29F9 big reverse solidus \xbsol
Numbers 4 & 8 are big operators, which is nice and unambiguous.
They're fine.
Almost everything else requires some discussion.
1. U+002F solidus
LaTeX defines \slash as 002F as a mathord.
The STIX table defines \slash as 2215 as a mathbin.
MathML normalises / to 2215, but I'd rather keep the distinction (if
only for backwards compatibility) between the two math types.
Proposed change: 002F defined as \slash as a mathord.
2. U+2044 fraction slash \fracslash
This should only be used for "vulgar fractions" and the like. And yet
Cambria Math uses it as its extensible delimiter. This is simply
wrong. (Nothing that the STIX group can do about that, however.)
3. U+2215 division slash \slash
As implied above, this should be called something else, since it has a
different math type than the ascii slash. In MathML, this is the
stretchy one.
Proposed change: define 2215 as \divslash (mathbin).
5. U+005C reverse solidus \backslash
\backslash is the same in STIX and LaTeX. Phew. But Cambria's
backslash doesn't grow. Frown. (This means Cambria has no "stretchy"
backslash.)
6. U+2216 set minus \smallsetminus
MathML calls 2216 "set minus" but amsmath calls it \smallsetminus.
Cambria Math uses the wrong glyph here (it uses the one that should
exist in 29F5).
7. U+29F5 reverse solidus operator \setminus
Except for the too-specific name and the confusion with MathML's
setminus, this one is fine. I'm under the impression that it should
not grow. It's missing in Cambria Math.
* * *
Any comments on all of this? It's taken me a little while to get my
head around it, so I might have missed something.
--
Will