...
The last tutorial showed how archetypes can hold data for persistence and reuse with some GLIF. While this is effective, an alternative approach is to use patient states as intermediate state objects. In other words the patient state can hold a value which is then accessible to GELLO, within the GLIF application. Currently we are allowing Boolean True False and Unknown but it is a work in progress. This approach avoids encroaching on GELLO immutablity immutability upon the EHR, which could technically be an issue when using archetypes (archetypes can be thought of as being part of the information model; and a tenet of GELLO is that it is side effect free). This tutorial will show a couple of examples of this use including GELLO for patient states. It finishes with showing GELLO for Sync nodes as alluded to in an earlier tutorial.
...
Patient states as preconditions
Another way to design things is to allow for some patient states as preconditions to then come together to produce an Action (a little bit like petri nets). Lets rearrange the GLIF we have done to demonstrate this.
Set up a new GLIF file and click on the Add branch button 
. (Hover on the buttons in the top menu to see their names) Put it in the middle of the pane at the top, and make it the first step. Edit the properties to make it 35 by 35 and tick the Invisible node button.
Put two patient states below this and link them to the Branch step. Name the patient states 'tachycardia?' and 'Aged over 75 yrs?'. Now put a Sync Node below these using the Add Sync Node button 
. Link the two patient states down to this.