Questions on Dependencies and identifiers

[Barringer, Kerry]

        I am still working through Challenge 1, modifiying my data model so
that it can completely model the text descriptions. I am now stuck on two
problems that arose when I was trying to work through the practical
implications of the model.

 First, I am stuck trying to adequately model the structure and dependencies
of the leaf apex characters
"apex obtuse or minutely mucronate within an apical notch". I am parsing
this out as:

Apex shape
        obtuse
        notched

Apex projection
        immucronate
        mucronate within notch (dependent on 'Apex shape - notched')

The model has an attribute for 'dependent on' under the character element.
Does the proper solution of this problem require a 'dependent on' attribute
as part of the //character/state element as well? Am I parsing the data
correctly?


        The first problem led me to the second problem, which is: how do we
identify the character or state another character depends on?  This is not a
problem when working with DELTA format data which has unique identifiers
already, but text descriptions do not.  Is an Xpath description adequate or
do we need to be able to have a structure that allows us to uniquely
identify what a character state describes?
        I originally thought a  unique identifier was needed to identify
missing data not explicitly encoded in the description and to provide a
pointer to characters or states that are other characters of states depend
on.  Now that I see how complex this may be to implement, I'm wondering if
another way would be better.
        I originally included an attribute called 'describes' under the
//character/state element. I thought that this could be used for two
purposes: (1) to add descriptive text to the character state and (2) to help
build a unique identifier for a character state.  The first use is no
problem; this structure allows an author to easily add "high' to the value
for the character state describing height for example.  The structure is
less useful for building an identifier for what the character state
describes.
        I thought I could build a unique identifier by combining the
character name and the 'describes' attribute. So for

        <Character>
                <CharName>Leaf</Charname>
                <State describes="PlaneShape" modifier="+/-">oblong</State>
        </Character>

The identifier 'LeafPlaneShape' identifies what the state describes.  This
allows you to recognize that even when there are multiple states (ie.
'ovate', 'round', etc.) they are all describing one aspect of the leaf.  If
nested characters are recognized, the identifier must get longer.
'ApexShape' or 'ApexProjection' wouldn't work, it would have to be
'LeafApexShape' or 'LeafApexProjection'.  If the nesting gets deep, this
gets awkward pretty fast. It would work, though.
        Do others think that having an identifier is necessary and, if so,
has anyone been able to come up with a better way to handle it? Is Xpath
adequate to our needs?

Thanks,
Kerry




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Kerry Barringer (Curator of the Herbarium)

Herbarium                     718-623-7318 (office)
Brooklyn Botanic Garden 718-941-4774 (fax)
1000 Washington Avenue  718-623-7312 (herbarium)
Brooklyn, NY 11225-1099   U.S.A.

kbarringer at bbg.org      http://www.bbg.org/
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