Types of data

[Jim Croft]

>Surely
>the way you measure an attribute depends on what you are going to use the
>measurements for, ultimately that's a question of precision. If there is a
>possibility that there will be a variety of uses (reuse) for the data, then
>an indictation of the degree of precision of the measurement would be highly
>desirable.

Source and precision stuff is surely important, but it is quite possible to
end up with major bloat and more meta than meaningful data.  This may not
be a problem but there is certainly a practical limit as to how far we can
or should go in this direction.

>Isn't it also important to distinguish whether the description refers to an
>actual leaf (ie. that leaf there, on that specimen is ovate) or whether you
>are making a generalisation about a taxon (ie leaves ovate to obovate)?

Most certainly.  I must admit I thought we were talking about taxon
descriptive  data, but therie is probalby no reason at all why the same
principles and data structure/definitions can not be used forthe
structures/features themselves.

>A taxon cannot have a leaf shape, only leaves can, and an actual leaf does
not
>usually vary in shape except through time.

Conversely, only a taxon can have, or not have, ovate leaves.  Is this a
generalization or a fact?  (and does it matter?)

><my_taxon_description>
>   <specimen>
>      <leaf shape="ovate" length_mm="10"/>
>      <leaf shape="ovate" length_mm="8"/>
>      <leaf shape="obovate" length_mm="25"/>
>   </specimen>
>   <specimen>
>      <leaf shape="ovate" length_mm="5"/>
>      <leaf shape="obovate" length_mm="31"/>
>   </specimen>
></my_taxon_description>

Conceptually I like this reperesentation - it is what we all do and may or
may not write down.  But as you say, maybe people want to know this, maybe
they don't...

jim

__________________________________________________________________________
Jim Croft ~ jrc at anbg.gov.au ~ http://www.anbg.gov.au/people/croft.jim.html
ph 02-6246-5500 ~ fx 02-6246-5248 ~ GPO Box 1600 Canberra ACT 2601