While it would be nice for ltree labels to support *any* printable character, it can't because symbols like `!` and `%` already have special meaning in the querying. This proposal leaves those as is and does not depend on any existing special character.
On Tue, Oct 04, 2022 at 12:54:46PM -0400, Garen Torikian wrote: > The punycode range of characters is the exact same set as the existing > ltree range, with the addition of a hyphen (-). Within this system, any > human language can be encoded using just A-Za-z0-9-.
IIUC ASCII characters like '!' and '<' are valid Punycode characters, but even with your proposal, those wouldn't be allowed.
