Is “fr, en; q=0.3” a valid Accept-Language value?

[Samuel Williams <[e-mail]>]

According to the RFC, it's okay to have *LWS between words and
separators. However, if you look at the specific ABNF for matching the
Accept-Language field, it doesn't allow for whitespace around the ;
character.

Here is the exact LWS specification:

implied *LWS: The grammar described by this specification is
word-based. Except where noted otherwise, linear white space (LWS) can
be included between any two adjacent words (token or quoted-string),
and between adjacent words and separators, without changing the
interpretation of a field. At least one delimiter (LWS and/or
separators) MUST exist between any two tokens (for the definition of
"token" below), since they would otherwise be interpreted as a single
token.

Here is the ABNF grammar:

   Accept-Language = "Accept-Language" ":"
                     1#( language-range [ ";" "q" "=" qvalue ] )
   language-range  = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )

Any advice would be appreciated. Thanks