- From: Dave Beckett <dave.beckett@bristol.ac.uk>
- Date: Thu, 04 Aug 2005 14:58:45 +0100
- To: andy.seaborne@hp.com
- Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
On Mon, 2005-08-01 at 13:38 +0100, Seaborne, Andy wrote:
> The current grammar does have a rather open production for QuotedIRIref
> (anything except space and >). An IRI reference can be relative. There is a
> comment referring to RFC 3987 in the grammar. An implementation is going to
> have to additionally process IRI references anyway to make them absolute.
> Without including the whol of teh IRI/URI grammar, we just parse IRIs.
>
> RFC 2396 defined "excluded charcaters" as:
> control = <US-ASCII coded characters 00-1F and 7F hexadecimal>
> space = <US-ASCII coded characters 00-1F and 7F hexadecimal>
> delims = "<" | ">" | "#" | "%" | <">
OK
How does these related to IRIs? "#" for exammple is excluded above, but
included in 'reserved' token below.
>
> RFC 3986 defines:
RFC 3986: Uniform Resource Identifier (URI): Generic Syntax
> pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
> pct-encoded = "%" HEXDIG HEXDIG
> unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
> reserved = gen-delims / sub-delims
> gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
> sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
> / "*" / "+" / "," / ";" / "="
OK
from RFC2234 on ABNF defines:
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39 ; 0-9
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
> RFC 3987 adds the characters of the UCS beyond U+007F to unreserved
RFC 3987 Internationalized Resource Identifiers (IRIs)
> ipchar = iunreserved / pct-encoded / sub-delims / ":" / "@"
> iunreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" / ucschar
> ucschar = %xA0-D7FF / %xF900-FDCF / %xFDF0-FFEF
> / %x10000-1FFFD / %x20000-2FFFD / %x30000-3FFFD
> / %x40000-4FFFD / %x50000-5FFFD / %x60000-6FFFD
> / %x70000-7FFFD / %x80000-8FFFD / %x90000-9FFFD
> / %xA0000-AFFFD / %xB0000-BFFFD / %xC0000-CFFFD
> / %xD0000-DFFFD / %xE1000-EFFFD
> iprivate = %xE000-F8FF / %xF0000-FFFFD / %x100000-10FFFD
ipchar and iprivate are mentioned only in:
iquery = *( ipchar / iprivate / "/" / "?" )
which is where "/" comes from in your summary below:
> Private can appear in a query string but not in the rest of the IRI.
>
> So the characters in an IRI reference are:
>
> ALPHA / DIGIT / "-" / "." / "_" / "~"
> ":" / "/" / "?" / "#" / "[" / "]" / "@"
> "!" / "$" / "&" / "'" / "(" / ")"
> "*" / "+" / "," / ";" / "="
> ucschar
> iprivate
> "%"
+ ":" (from ipchar)
> and the rq23 grammar becomes:
>
> QuotedIRIref ::= '<' IRICHAR* '>' /* An IRI reference : RFC 3987 */
>
> IRICHAR ::=
> [A-Z] | [a-z] | '=' | '.' | '_' | '~' |
> ':' | '/' | '?' | '#' | '[' | ']' | '@' |
ok, you added ':'
> '!' | '$' | '&' | ''' | '(' | ')' |
> '*' | '+' | ',' | ';' | '=' |
> '%' |
> [#xA0-D7FF] | [#xF900-FDCF] | [#xFDF0-FFEF] |
> [#x10000-#x1FFFD] | [#x20000-#x2FFFD] | [#x30000-#x3FFFD] |
> [#x40000-#x4FFFD] | [#x50000-#x5FFFD] | [#x60000-#x6FFFD] |
> [#x70000-#x7FFFD] | [#x80000-#x8FFFD] | [#x90000-#x9FFFD] |
> [#xA0000-#xAFFFD] | [#xB0000-#xBFFFD] | [#xC0000-#xCFFFD] |
> [#xD0000-#xDFFFD] | [#xE1000-#xEFFFD] |
> [#xE000-F8FF] | [#xF0000-FFFFD] | [#x100000-#x10FFFD]
>
>
> [I would be very grateful if someone checked this]
looks right.
> An alternative is to exclude the illegal characters:
>
> That is (RFC3986):
> 0x00-0x20, 0xFF, '<' '>' "`"
>
> but with RFC3987 it isn't that short:
>
> FDD0-FDEF
> FFF0-FFFF
> 1FFFE, 1FFFF
> 2FFFE, 2FFFF
> etc for 3,4,5,6,7,8,9,A,B,C,D,E,F
> 10FFFE, 10FFFF,
> 200000 onwards
I'd hope there is some advice about this in some document nearby the
Character Model for the World Wide Web 1.0: Fundamentals
http://www.w3.org/TR/2005/REC-charmod-20050215/
"Publicly interchanged content SHOULD NOT use codepoints in the private
use area."
http://www.w3.org/TR/charmod/#sec-PrivateUse
which includes "the Private Use Area (PUA) (U+E000-F8FF) and planes 15
and 16 (U+F0000-FFFFD and U+100000-10FFFD)."
There are probably more...
Dave
Received on Thursday, 4 August 2005 13:58:53 UTC