Types of data

Jim Croft jrc at ANBG.GOV.AU
Fri Nov 26 05:51:54 CET 1999

>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

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
>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?)

>   <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>

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 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

More information about the tdwg-content mailing list