On 1/8/2026 7:09 AM, Ivan Panchenko via Unicode wrote:
It is sometimes assumed that the S-shaped bag delimiters (U+27C5 and
U+27C6) are for multisets (because multisets are also called “bags”).
However, looking at the attestation shown in N2680, they appear to be
used around a well-formed formula rather than for a multiset. This
suggests that “bag” simply describes their shape, though the
description “The second pair of proposed characters is a set of
s-shaped delimiters used as bag delimiters” in the proposal does make
it sound as though they were multiset delimiters.
https://www.unicode.org/L2/L2003/03410-n2680-add-math-chars.pdf
Given that the referenced document is no longer available, does anyone
know what these characters mean?
"We", that is the "math" subgroup of the PAG did some digging and came
up with both an archival location for the missing document as well as
citations that confirm usage in the context of multiset.
https://web.archive.org/web/20041109101630if_/http://www.ma.utexas.edu:80/users/jcorneli/h/Xi.ps
the quoted text is section 35 page 14 of this version
And
the \lbag and \rbag symbols were in the 1994 version of the fonts
https://web.archive.org/web/20010110005900/http://www.tex.ac.uk/tex-archive/fonts/stmaryrd/stmaryrd.dtx
|% \title{The St Mary's Road symbol font} % \author{Jeremy
Gibbons \and Alan Jeffrey} % \date{Version 2, March 1994} % %
\maketitle % % \section{Introduction} % % This is a brief guide
to the St Mary's Road symbol font, a new symbol % font for \TeX\
and \LaTeX. It is designed to live with the American %
Mathematical Society's fonts, contained in {\tt amssymb.sty}. %
% It provides a number of new symbols, including ones for
derivation of % functional programming (such as $\varcurlyvee$,
$\moo$ and % $\merge$), process algebra ($\llfloor$, $\oblong$
and % $\lightning$), domain theory ($\bigsqcap$), linear logic %
($\binampersand$ and $\bindnasrepma$), multisets ($\Lbag x
\Rbag$, % $\nplus$, and $\subsetpluseq$) and many more. |
as a conclusion we think there's nothing that needs to change.
A./
PS: I'm merely acting as reporter.
