Revisiting mime-types and file extensions

[Michel Fortin]

Le 2007-06-21 à 12:35, Phil Mocek a écrit :


> Can anyone confirm that having the HTML fragment identifier

> formatted as Thomas proposes is valid?  Both this [W3C design

> issue paper][1] and [Wikipedia article][2] suggest otherwise, but

> I'm not sufficiently familiar with this to say for certain.

>

> [1]: <http://www.w3.org/DesignIssues/Fragment.html>

> [2]: <http://en.wikipedia.org/wiki/Fragment_identifier>


The content for the id attribute for HTML 4 must obey [this rule][3]:


> ID and NAME tokens must begin with a letter ([A-Za-z]) and may be  

> followed by any number of letters, digits ([0-9]), hyphens ("-"),  

> underscores ("_"), colons (":"), and periods (".").


[3]: http://www.w3.org/TR/html401/types.html#type-name


For XML, and by extension XHTML, it must obey the Name construct,  
which is defined as such [in the spec][4]:

     NameChar ::= Letter | Digit | '.' | '-' | '_' | ':' |  
CombiningChar | Extender
     Name ::= (Letter | '_' | ':') (NameChar)*

[4]: http://www.w3.org/TR/REC-xml/#NT-Name


Basically, HTML and XML both disallow digits as the first character  
of the id attribute. That's why the version number is preceded with a  
"v" in my profile page.

While invalid as an XML or HTML id value, a fragment identifier  
starting with a digit is still perfectly correct in a URL. Here's the  
definition of URL fragment according to [RFC 3986][5]:

     fragment    = *( pchar / "/" / "?" )
     pchar       = unreserved / pct-encoded / sub-delims / ":" / "@"
     unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
     pct-encoded = "%" HEXDIG HEXDIG
     sub-delims  = "!" / "$" / "&" / "'" / "(" / ")"
                 / "*" / "+" / "," / ";" / "="

[5]: http://tools.ietf.org/html/rfc3986


Michel Fortin
michel.fortin at michelf.com
http://www.michelf.com/