Master variables can be defined once and applied to each created process definition.  

For example, if customerID is used on every definition, instead of defining the variable for each definition, customerID can be determined using the master variable screen. Once the variable is defined using the master variables, each new definition will automatically have the “customerID” variable. 

Take a look at the straightforward master variable UI, designed to make defining variables easier and more manageable. 

Add variables by entering their names and selecting a data type. Remove any variables by selecting them from the list. The 'Variables / Globals have default values based on type' functionality in the Process Instances page allows you to add and remove variables.

• Variables and globals have '0' for the 'Number' data type
• Variables and globals have ' ' for the 'String' data type
• Variables and globals have 'Current date and time' for the 'Date' data type
• Variables and globals have 'false' for the 'Boolean' data type