Custom Actions is one feature that I haven't used a lot in Dynamics CRM 2013. I am exploring a concept that involved utilising this feature. The official MSDN document and the associated blogs have been a good source of information to understand the basics, but I have hit a road block. I created a new custom action with a EntityCollection output parameter. Currently, this is what the MSDN documentation on custom actions says about EntityCollection parameter.

EntityCollection argument values can’t be set in the user interface for conditions or actions. These are provided for use by developers in custom code. More information: Create your own actions

I am still unclear as to how to set the value for EntityCollection output parameter, as I have already defined it in the action and activated the action. I am gathering that you need a custom workflow step in Action to set the value of this EntityCollection output parameter. But there is no sample code that says you how this could be achieved. Is there a reference to the Custom Action hiding some where in the execution context, that I have to access to set the output parameter? Has anyone dealt with such a scenario before and can elaborate to what the solution is? Thanks.