[1] RFC 7749 - The "xml2rfc" Version 2 Vocabulary (2016-02-04 22:54:51 +09:00 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.