Delta-like descriptions for Thiele 0.3 draft

[don kirkup]

from Kevin Thiele;

> | Ah, Jun Wan reminds me that uniqueness of ID attribute values is
> | imposed by XML itself. So in the Delta-like descriptions, the choices
> | I see are to generate unique ID's that encode the context or to use a
> | different attribute than ID, perhaps something like TDWGID. In the
> | former case one might have something like:
> |         ID="F.1" to mean that this is an id for feature 1
> |         ID="F.V.1.2" to mean that this is value 2 for feature 1
> | In XSLT, these are parseable with the XPath string functions, so that
> | nothing more than XSLT is needed to associate an IDREF with the object
> | having the associated ID.
>
> This is a nuisance. TDWGID I think is not a likely candidate.
>
> Using your first option, one could use simply:
> ID="1" (id for feature 1)
> ID="1.2" (id for value 2 of feature 1)
>
> This may then perhaps even be handy. Then again, by constraining like this
> it would quickly become a nightmare to add or re-arrange features
> or values.
>
> Is this the first case where we're being imposed upon by XML and
> we start to
> wear the cost of its advantages? Are there any other ways out?

Rather than inserting 'ID' type elements within the XML, you could instead
define <xsl:key> elements in a xsl stylesheet and then use the XPATH  key()
function to access the values. The key() function works in pretty much
identical way as the XPATH id() function, but a key (unlike an id) doesn't
need to be unique.
don