What is a link really?  It's a reference from any place to another.  A
place, in this situation, means somewhere/somedata that a human could
access and a connection from that data to some other piece of data.

Not all targets of links can legitimately and fully be represented by
URLs.  This is, in my opinion unfortunate.

Normally, at least part of the link can be represented by a url.  

There seem to be several cases

* links which are illegal within their proper URL scheme

* links which are an extension of normal protocol

* links which require extra data to be activated

* links which don't (yet) have a defined scheme

Here are some examples.

- a post request for a query of a database

we can represent some protocol location like

http://bigdb.example.com/cgi-bin/people-list

and we may not be able to represent

first-name=john

because of the limits of the http URL format.

- a reference to a specific fragment within the link

we can represent the link

http://www.example.com/mydoc

but the fragment is not legitimately part of the URL since the #
character is illegal in a URL...

Each of these references a specific piece of data, which should have
resonably static meaning and which it would be useful to do link
checking on.

Now sometimes there are things which we can't reasonably represent by
a URL because they are not meaningful in the current situation.

- a post request that should be sent to add an entry to the database.

Although there may be data returned, the success or failure of a
request doesn't directly tell us whether or not the link is working
since.

The most that we can do is that we can make a reference to something
which will ask the database if it is still there and functioning.  


Another aspect of the handling of links which do not correspond
directly to a "resource" is that often, multiple links should be
resolved in one resource access.  E.g. when accessing a HTML text, we
should occasionally check all of the 


Ways to deal with 


current way - 

	ignore the fragments etc.

another way - 

	separate link in database for every single variation
	use link database as reference for link testing / status

	Link object has to know how to reference other link objects


	keep a list of fragments in the link - 
		tester uses it to access the other fragments
		tester updates

as far as fragments in http urls go, I think that these are better to
see as part of content verification.  
