> Date: Sun, 13 Apr 2025 10:45:15 +0000 > From: Nitai Sasson via Unicode <unicode@corp.unicode.org> > > > I just stumbled upon this: > > https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-23/#G13001 > > > Three pairs of deprecated format characters are encoded in this block: > > > > Symmetric swapping format characters used to control the glyphs that > > depict characters such as “(” (The > default state is activated.) > > > > [...] > > > > Symmetric Swapping. The symmetric swapping format characters are used in > > conjunction with the class of > left- and right-handed pairs of characters (symmetric characters), such as > parentheses. The characters thus > affected are listed in Section 4.7, Bidi Mirrored. They indicate whether the > interpretation of the term LEFT or > RIGHT in the character names should be interpreted as meaning opening or > closing, respectively. They do > not nest. The default state of symmetric swapping may be set by a > higher-level protocol or standard, such as > ISO 6429. In the absence of such a protocol, the default state is activated. > > > > From the point of encountering U+206A INHIBIT SYMMETRIC SWAPPING format > > character up to a > subsequent U+206B ACTIVATE SYMMETRIC SWAPPING (if any), the symmetric > characters will be interpreted > and rendered as left and right. > > > > From the point of encountering U+206B ACTIVATE SYMMETRIC SWAPPING format > > character up to a > subsequent U+206A INHIBIT SYMMETRIC SWAPPING (if any), the symmetric > characters will be interpreted > and rendered as opening and closing. This state (activated) is the default > state in the absence of any > symmetric swapping code or a higher-level protocol. > > These deprecated format characters differ the ones proposed now in the > following ways: > - They only apply to characters that have the Bidi_Mirrored property, meaning > they don't solve the use cases > raised. > - They apply to an entire span of text, whereas the proposed characters bind > to a single preceding character > each time. > - It is ambiguous, at least to me, whether symmetric swapping should be > inhibited or activated after U+206B > ACTIVATE SYMMETRIC SWAPPING .. U+206A INHIBIT SYMMETRIC SWAPPING. The > proposed characters > would leave no ambiguity.
Doesn't the BPA algorithm, nowadays part of UAX#9, supersede what the above intended to do?
