sf-string - structured fields string as defined in RFC8941

Base type: string.

The sf-string format represents a structured fields string as defined in RFC8941.

sf-string = DQUOTE *chr DQUOTE
chr       = unescaped / escaped
unescaped = %x20-21 / %x23-5B / %x5D-7E
escaped   = "\" ( DQUOTE / "\" )

Strings are zero or more printable ASCII [RFC0020] characters (i.e., the range %x20 to %x7E). Note that this excludes tabs, newlines, carriage returns, etc.

Strings are delimited with double quotes, using a backslash (“") to escape double quotes and backslashes.

This format is appropriate for a header value that must conform to the sf-string structured field definition.