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Re: VCTF Use Cases [RE: Verifiable Claims Telecon Minutes for 2016-04-19]

From: Steven Rowat <steven_rowat@sunshine.net>
Date: Tue, 19 Apr 2016 22:16:09 -0700
To: Credentials CG <public-credentials@w3.org>
Message-ID: <57171099.4030607@sunshine.net>
On 4/19/16 10:12 AM, msporny@digitalbazaar.com wrote:
> Use cases doc is suffering from
>    lack of reviews.

I have some comments on this VCTF use-cases draft, which I think is 

I've left them in the order I made them while reading.

[No issues until...]

"Status of This Document"

Minor suggestion -- why not link the words "Charter for a Verifiable 
Claims Working Group" to the Charter. Most other things are linked, 
and this one is specifically stated there as needing to be read in 
conjunction with the Use Cases document. So I expected a link.

On reading the first term, 'claim', and then following the two terms 
introduced in it, 'entity', and 'identity', to their definitions later 
in the list, it took me a couple of readings of all three to 
understand that there was no recursive loop set up between Entity and 
Identity. At first it seemed like there might be, which was 
disorienting my ability to continue down the list.

What I mean is: what is presupposed here by the Editors -- as I 
eventually understood it -- is that an 'entity' actually exists in the 
world somewhere (otherwise it couldn't make a statement, and nothing 
else would matter). Whereas the 'identity' being defined only exists 
insofar as the verifiable claim process is completed, or at least 

So: 'identity' is being *defined by the steps of the system*, whereas 
'entity' is *pre-existing outside the system*.

I think this might be spelled out better, especially in that first 
encountering. The fact that the listing of terms is alphabetical and 
so 'claim' is encountered first is essentially random, and it might be 
good to be careful that the first encountering of 'entity' and 
'identity', which happens here, doesn't allow the reader to think 
that, say, both entity and identity exist outside the system, or both 
are only defined within the system, or that identity exists outside 
and entity is defined inside it.

In other words, if the naive reader has some biases about those two 
words 'entity' and 'identify' already and, without guidance at this 
point, makes assumptions about how they're used, then in three out of 
four of those assumptions they're going to be wrong and have to 
re-orient themselves again later. Maybe best to correct them right at 
the start. :-)

If 'identity' is used again here without a solution to the problem of 
definition I just described having been given, this could allow the 
reader to continue to entrench an incorrect assumption about 'identity'.

"Credential consumer"
Ditto about 'entity'. More entrenching of possible wrong understanding.

Now there is a clear statement; but I suggest that this statement 
needs to go at the start. So I believe it would be best not to use 
alphabetical listing. I think this statement is a key one and should 
be encountered early or first.

In fact, looking at the next two, 'Holder' and 'Identity', I now think 
overall that "Terminology" should be re-ordered to unfold in a way 
that makes it easiest for the reader to both map the terms with their 
specialized meanings and to follow the flow of the basic mechanism of 
the VC.

I think there are a small enough number of terms that 
alphabetical-ness isn't really required. It's more important to follow 
the flow and definitions correctly the first time through than to be 
able to find them quickly later. It's not hard to scan ten bold words 
and find the one you want, whatever order they're in.

"4.1.1 Uniquitous Claim Issuance"
"Uniquitous" -- I found no match in three dictionaries I tried. Google 
search shows 26 million hits for 'ubiquitous' and 21 thousand for 
'uniquitous'. I's an interesting word, but that's three orders of 
magnitude. I think it might be best to avoid it, in the interests of 
less obfuscation (3 million hits. ;-) ).

First scenario - typo: needs period after 'money laundering'.

All scenarios: why are some uses of 'credential' and other glossary 
terms linked, and not others. I suggest either link all, link none, or 
link only those in the first scenario under each section.

All scenarios: In first two scenarios (Jane, Midbank, Joleen, Mega U.) 
the goals of the person are not immediately apparent; I had to puzzle 
them out a bit, especially in the second, the 'extended transcript'. 
Whereas the third and fourth ones are simpler and clearer. I suggest 
reversing the order, and where possible, in all sections, put the 
simplest and clearest instances first.

"Editor's note" : doesn't make sense. We're in 4.1.2, so I don't know 
what referent is.

"4.2.1 Issuer Revokes Claim"
Barney and Jane have been encountered before. Other names are new, 
like John and Big Bank. I think this is causing my brain to lose the 
meta-plot here, and get confused about who is what and what's 
happening where. So I think either:

   a) a small group of consistently-named people and entities should 
be followed through all the steps, start to finish of all the 
use-cases; or

   b) use new names in all cases for each instance in every use case.

Otherwise I think some human brains will naturally strain to see the 
pattern, and expect the stories to continue (since some of them do), 
and be confused about whether they do or don't.

Plus, either way, I think the naming of entities could be simplified 
and some deleted; it seems preferable to me to say John or Jane uses 
'a bank' in a given scenario. [For example, I found I was relieved 
when reading the section 4.4.3 Pseudo-Anonymity scenarios, which had 
only one named entity in each of the first two scenarios -- June and a 
'beer and wine store', John and 'a clinic'. I found these easier to 

"4.3.1 Portability of Claims"
Again...with all due respect, in my opinion the possible tangents 
introduced in people's minds by BigBank, WallStreetCo, Wossamotta U., 
and Moosylvania -- such as, perhaps, "Too Big To Fail" and/or college 
humor -- are unnecessary and distracting in a document as important 
and potentially difficult to understand as this one. It sounds boring 
maybe, but I think as many terms as is possible should be made 
neutral, so that the ones being defined will stand out without 

"4.4.2 Consumer Verifies Claim"
What is the "credential identifier". Is this related to 'identity'? 
I'm lost in this paragraph from that term onwards. And the term 
doesn't exist anywhere else in the document (search doesn't find it).

That's it, no issues after that.  :-)

Steven Rowat
Received on Wednesday, 20 April 2016 05:16:40 UTC

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