[1] RFC 7749 - The "xml2rfc" Version 2 Vocabulary (2/4/2016, 1:54:51 PM 版) <https://tools.ietf.org/html/rfc7749#section-4>
non-breaking hyphen (U+2011)Similarly, this represents a hyphen character where no linebreaking ought to occur.
non-breaking hyphen (U+2011)
Similarly, this represents a hyphen character where no line
breaking ought to occur.
Google search: U+2011