I am wondering if anyone has seen or found a list of resource types by workflow type when creating an custom workflow. This tool is very lacking, and does not have dictionaries or encyclopedia listed that I can see.
What you are showing is the element that defines the workflow - i.e. the anchor for your answers inside the workflow. To see the available resources, one must look at the "add" list within the workflow editor.
In addition some resources are accessible via the context menu rather than directly within the workflow.