A really clear way to specify this is to say that an id is a functional relation between
an entry and a identity construct.
This implies: -An Entry can only have one id. -Different Entries can have the same id.
Of course because there is a bit of a confusion as to what is meant by an Entry
the above sounds paradoxical.
It is a bit like the relation the body of a US citizen has to a social security number.
The body of a US citizen at a time has a functional relation to a SS number. Any such body
has only one SS number. But because when we eat and breath our bodies change it turns out
that different bodies have a relation to the same SS number. The different bodies, are time
slices of the same US citizen. The group of these time slices is identified by the social
security number. So that the relation between the SS number and set of such citizen slices,
namely the relation between a SS number and the citizen is both functional and inverse functional.
When this group speaks about an Entry as it appears in the Feed
<feed>
<entry>
<id>tag:bblfish.net/entry1</id>
...
</entry>
...
</feed>you are really speaking about an entry version. But because when people sit down and write
an entry they are looking at the present version of the entry, and this is what they use
to identify the sequence of entries that form the unique Entry over time, there is a confusion
of what is being talked about.
It is a little as if I spoke to someone and identified the body I am seeing at present
with the person that body is a temporal part of.
So when above I say:
-An Entry can only have one id. -Different Entries can have the same id.
What we mean is
- the Entry Version can only have one id
- any two Entry Versions that have the same id are different versions of the same Entry.
So now one should define what that type of entry is. And that is simple. It is the Collection
of all Entry Versions that have the same id.
Henry
On 4 Feb 2005, at 22:10, Mark Nottingham wrote:
Graham, the issue here is that the spec can be interpreted in a number of ways, which is not good. You seem to agree with that below, correct?
Separately, there's the issue of what it *should* say. Tim and now you say that you have a good idea of what you want it to say; I'd be very interested to see how you'd specify that. Can you suggest some spec text?
On Feb 4, 2005, at 1:00 PM, Graham wrote:
On 4 Feb 2005, at 8:44 pm, Mark Nottingham wrote:
I.e., just because it's a "permanent, universally unique identifier" doesn't mean you're not able to use it twice to talk about a single entry;
I disagree, as I've said before. The only literal interpretation is that you can't serve the same entry twice with the same id. We know it doesn't mean that, but the spec just doesn't define in which axis "unique" is meant to apply.
Graham
-- Mark Nottingham http://www.mnot.net/
