Create custom types in vRO

Hello everyone,

I am trying to figure out how to create custom types in vRO? For example,I was looking through AWS vRO plugin that I downloaded and I can see custom types such as AWS:EC2InstanceType. When the workflow runs this pulls in instance types from AWS. I am trying to figure out where this is defined and how it does that so that I can customize it.

thanks

Nuz