The data for some categorical Data-Fields has a tree structure whereby the available possible values are arranged as a hierarchy of increasingly detailed nested categories. This coding structure allows information to be stored fully when the level of detail within individual items varies.

When viewed within the context of a Data-Field, a Count column shows the number of items which have either the code indicated or are part of a hidden subset of it. As the tree levels are expanded, the count next to a particular item may decrease as the sub-items below it become visible.

When viewed within the context of a Data-Coding, the Node/Parent columns show the structure within the tree.

• The Node column is an internal ID generated for each element of a data-coding.
• The Parent column indicates the Node value of the level 'above' each coding entry in the tree - with the word "Top" indicating that a particular code is at the highest level of the hierarchy.

Warning: some older browsers/computers take a long time to render the larger tree datasets and this may result in superfluous pop-up messages being generated by the browser before the page has fully loaded.