Workflow Delivery Properties
You can specify key value pairs for a particular workflow. When a workflow is delivered using a Delivery Option, the Workflow Delivery Properties are available to certain delivery option types for use in their Templates (XDS or Email delivery options)
The key must only contain alpha characters and underscores. The value may contain any characters.
The key name determines the name of the variable in the delivery option template.
Eg: If the key name set for a delivery property is 'category' then in the XDS document template, you can substitute the value of this property using {{ workflow.delivery_properties.category }}