The OCR Trigger is basically an user specified area on a document in which if a certain condition is met, usually the existence of a piece of text or a regular expression, a user specified action will be performed. Depending on the trigger logic set on the Trigger Properties when the desired text or regular expression is found or not on the area specified by the user the desired action is performed.
Actions for triggers are the following:
Split documents on several different ways;
Set Document type;
Set position reference for other data capture elements;
Set value or default value for a field;
Report Split for complex tables;
Execute a VBScript for custom setups;
Create a reference line;
Create anchor text;
Do nothing.
To change the action a trigger will perform and it's logic options and other settings first select the trigger and then navigate to the Properties panel to visit the OCR Trigger Properties menu.
This trigger is searching for something similar to "Invoice No." and then creating a position reference for the linked elements, such as the OCR Zone linked to the Data Field Scan Date.
When you reference OCR zones to a floating trigger you will see green link arrows indicating the position reference: