Hi Martin,

Yes, using the approach I am advocating for uncertain quantities means
that @cert would specify confidence that the actual value lies within
the specified range. It would not specify your confidence in the @when
value. Thus <date @when="115" @notBefore="100" @notAfter="155"
@cert="high"/> would be translated as "I am certain beyond reasonable
doubt that the actual date of this thing lies between 100 and 155 CE.
FWIW, I think that its most probable date is 115."

This approach will work in many cases but certainly not all. As Gabby's
examples show, each of @when, @notBefore and @notAfter can be uncertain.
A general solution needs to be able to treat each of these things as an
uncertain quantity. We can't have attributes on attributes so it would
seem that stand-off markup is required for difficult cases.

Best,

Tim Finney

On Wed, 2008-01-30 at 04:35 -0800, Martin Holmes wrote:
> Hi there,
> 
> Tim Finney wrote:
> [snip]
> > Thus, an adequate description of the magnitude of an unknown quantity
> > requires:
> > 
> > (1) an estimate of the quantity (e.g. 115)
> > (2) an interval in which the quantity is thought to lie (e.g. +/- 50)
> > (3) the confidence attached to the assertion that the actual value lies
> > within the interval (e.g. "high", "medium", "low").
> 
> Using  this approach, if I write this:
> 
> <date when="1640" notBefore="1620" notAfter="1660" cert="low"></date>
> 
> the assumption would be that the low certainty applies to the @notAfter 
> and @notBefore values, not to the @when value.
> 
> Cheers,
> Martin
>