Best practice for meta data in a html document?
I work on a large scale, high volume, public facing web application. The successful operation of the application is very important to the business, and so there are a number of MI tools that run against it.
One of these MI tools essentially looks at the html that is sent to the browser for each page request (I've simplified it quite a lot, but for the purpose of this question, its a tool that does some analysis on the html)
For this MI tool to get the data it needs, we put meta data in the head element. Currently we do it as html comments:
<!doctype html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" class="">
<head>
<!-- details = 52:AS6[rxSdsMd4RgYXJgeabsRAVBZ:0406139009] -->
<!-- policy id = 1234567890 -->
<!-- party id = 0987654321 -->
<!-- email address = [email protected] -->
<!-- error = 49 -->
<!-- subsessionid = bffd5bc0-a03e-42e5-a531-50529dae57e3-->
...
And the tool simply looks for a given meta data comment with a regex
As this data is meta data, I'd like to change it to html meta tags because it feels semantically correct. Something like this:
<!doctype html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" class="">
<head>
<meta name="details" content="52:AS6[rxSdsMd4RgYXJgeabsRAVBZ:0406139009]" />
<meta name="policyId" content="1234567890" />
<meta name="partyId" content="0987654321" />
<meta name="emailAddress" content="[email protected]" />
<meta name="error" content="49" />
<meta name="subsessionid" content="bffd5bc0-a03e-42e5-a531-50529dae57e3" />
...
This feels more semantic, and I can get the MI tool to work with it no problem - just a case of changing the regexes. However it now gives me a problem with the w3c validator. It wont validate because the meta names I'm using are not recognised. I get the error "Bad value details for attribute name on element meta: Keyword details is not registered." and it suggests I register these name values on the WHATWG wiki.
Whilst I could do this it doesn't feel right. Some of my meta tags are 'generic' (such as error and emailAddress) so I could probably find an already registered name value and use that. However, most of them are industry/organisation specific. It feels wrong to register a public name value called subsessionid or partyId as these are specific to my organisation and the application.
So, the question is - what is considered best practice in this case? Should I leave them as html comments? Should I use meta tags as above and not worry that w3c validation fails? (though that is increasingly important to the organisation) Should I attempt to register my meta name values on WHATWG wiki, but knowing they are not very generic? Or is there another solution?
Appreciate your thoughts, cheers
Nathan
Edited to show the the final solution:
The full answer I'm going with is as follows. Its based on Rich Bradshaws answer, so his is the accepted one, but this is what I'm going with for completeness:
<!doctype html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" class="">
<head>
<meta name="application-name" content="Our app name"
data-details="52:AS6[rxSdsMd4RgYXJgeabsRAVBZ:0406139009]"
data-policyId="1234567890"
data-partyId="0987654321"
data-emailAddress="[email protected]"
data-error="49"
data-subsessionid="bffd5bc0-a03e-42e5-a531-50529dae57e3"
/>
...
This validates, so all boxes ticked :)
Answer
W3C validation is meaningless. HTML != XML, so there isn't any schema to validate it. No browser will choke because you added a meta element with an unregistered name. If you really are worried, you could use the data attribute on a meta element like:
<meta data-details="52:AS6[rxSdsMd4RgYXJgeabsRAVBZ:0406139009]" data-policyId="0123456789" />
at least then you know no future spec will give meaning to your data.
For more info read: http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#custom-data-attribute