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[widgets] P&C Last Call comments, zip-rel-path ABNF

From: Marcin Hanclik <Marcin.Hanclik@access-company.com>
Date: Mon, 1 Jun 2009 00:44:38 +0200
To: "public-webapps@w3.org" <public-webapps@w3.org>
Message-ID: <FAA1D89C5BAF1142A74AF116630A9F2C0A26D782E2@OBEEX01.obe.access-company.com>
Error in ABNF:
localized-folder vs. locale-folder

Error with ABNF
utf8-chars       = safe-chars / U+0080 and beyond
"and beyond" does not fit here
Section 2. of RFC2279 shows that all UTF-8 characters above U+0080 are encoded with byte values over 0x80.
So utf-8 production equals to cp437 production on the byte level within the context that is important for us.
So both productions can be equalized and removed, since allowed-char may be used.
I think the problem is similar to this one about encoding (I just had a brief look on it):
http://lists.w3.org/Archives/Public/public-html/2009May/0643.html

Error with ABNF
cp437-chars      = safe-chars / x80-FF
should be according to RFC2234:
cp437-chars      = safe-chars / %x80-FF

Due to many issues I would rewrite the whole ABNF as follows.
ABNF issues, additionally to the above, are:
1. plural form used for just "one-of" value
2. the zip-rel-path may have problems with existence, since all productions are optional. The below format seems equal and is
shorter
3. the production of file-name is wrongly specified, since there file-extension could appear up to 254 times in a file name
4. I am not sure whether the file extension could be more than 3 chars or not in the existing ABNF?
If so, the actual file name shall match 2 rules simultaneously, e.g.:
file-name1       = 1*allowed-char [ "." 1*allowed-char ]
file-name2       = 1*254 ( allowed-char )
Matching of those 2 rules is not expressible in ABNF, so prose would be needed.

New ABNF (problem of file extension length as above still remains):
**************
A valid Zip relative path is one that case-insensitively matches the production of Zip-rel-path in the following [ABNF] that
operates on bytes, not on characters, i.e. after any encoding (CP437 or UTF-8) has been applied:

zip-rel-path     = [ locale-folder ] [ *folder-name ] [ file-name ]

locale-folder    = "locales" "/" Language-Tag "/"
folder-name      = file-name "/"
file-name        = base-name [ file-extension ]
file-extension   = "." 1*3 ( allowed-char )

base-name        = 1*250( allowed-char )
allowed-char     = safe-char / %x80-FF
safe-char        = ALPHA / DIGIT / SP / "$" / "%"
                    / "'" / "-" / "_" / "@"
                    / "~" / "(" / ")" / "&" / "+"
                    / "," / "." / "=" / "[" / "]"
**************

Authors need to keep path lengths below 250 bytes. Unicode code points can require more than one byte to encode, which can result in
a path whose length is less than 250 characters.
should be
Authors need to keep path lengths below 250 bytes. Unicode code points may require more than one byte to encode a character, which
can result in a path whose length is less than 250 characters to be represented in more than 250 bytes.

UTF8-chars
should be
utf8-chars or utf8-char or something new (after the ABNF is updated) .

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Received on Sunday, 31 May 2009 22:45:18 GMT

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