Earlier in the knowledgebase we talked about the interaction between instances of the Information, Concept and Guideline Models. An example of each, in turn could be the EN 13606 Reference Model ; SNOMED-CT and GLIF. We think GELLO acts as an interface between the Guideline and Concept models as well as between the Guideline and Information models. Medical Objects uses GELLO R 2 to:
- query and process information model and concept model data from a guideline model instance
- perform 'script' operations on data held within archetype instances
Examples of the latter are to be discussed in this section and include:
- node value calculation
- node visibility
- node value validation
- node value initialisation
- reference range calculation
Where algorithms return significant calculate values, it is wise to flag the system generated nature of the result data and offer clinicians access to the algorithms used, where this is possible, feasible and sensible to do so.
Now some example GELLO code will be offered.
Open CEN-Apple.v1.xml with the Template Editor from File-Archetype_apple_example.zip
Click on ENTRY or one of the ELEMENTS. On the RHS note the tags with 'No Gello' as attributes. What we are going to do is add some GELLO to this archetype. Let's add some more elements to enable this. Left click, then right click on ENTRY and add two new ELEMENTS to the bottom of the Definition tree. Name them 'Number' and 'Total Cost". Make their data types mtIntegerRange and mtQuantity as before. Make the units for 'Total Cost' to be '$' and the number of decimal places to be 2. If you don't know how to do this or don't remember, go back to Simple worked example. Click on 'Number' and move it up the tree to between 'Cost' and 'Weight' by clicking on the Move up button 
. Position 'Total cost' likewise between 'Weight' and 'Variety notes'.
Click on the following links for worked examples based on the apple archetype: