This page last modified: Nov 02 2006
- Multivalued columns must be sub-elements. If a column contains a list
or an array, that column must be a sub-element.
- Columns with a single value should be attributes, not elements.
- An element used as a container should always have the same set of
sub-elements. If the set of sub-elements varies, then it is a
different type of record and the containter element should have a
different (unique, new) name to reflect the different purpose. If
some sub-elements (columns) are optional, those sub-elements should
ideally have a 'missing data' value, but could have an empty value
(essentially null) instead.
- Any column which will have sub elements must become an element (and
cannot be an attribute).
For example a symposium with several sessions, each session has
several presenters.
<symposium>
<session title="a">
<presenter name="ralf"/>
<presenter name="bob"/>
<presenter name="mary"/>
</session>
<session title="b">
<presenter name="pat"/>
<presenter name="tad"/>
<presenter name="jordan"/>
</session>
</symposium>