[whatwg] "pattern" attribute definition

[Malcolm Rowe]

Hi Ian, 

When we define 'pattern', we define it in terms of an ECMAScript RegExp 
object (or so it seems), but we don't define what the values of the 
'ignoreCase' and 'multiline' properties of a hypothetical object should be. 

I know that 'multiline' was present at some point, and it's now been dropped 
 - what was the reason for that? I do think that we should explcitly mention 
whether the expression should be evaluated in a case-sensitive way or not. 

Secondly, is '/' special inside an expression? In a 'normal' regexp (in 
ECMAScript or perl), you'd expect to have to escape it, since the language 
uses that symbol to terminate the pattern definition - though in perl, you 
could also use another character if you wanted to, for example: m|^/etc/|. 

Would we expect 'pattern="/etc/.*" to work? Would 'pattern="\/etc\/.*" work 
just as well? Should we include a note around that area in the definition of 
'pattern'? 

Regards,
Malcolm