The clue is in the name - it's Velocity. Or strictly, Velocity Template Language
Start at http://velocity.apache.org/ which is a dreadfully laid out site as it's really hard to find the docs you actually need, and I find my bookmark of http://velocity.apache.org/engine/devel/user-guide.html far easier to use for navigation
Introduction Many users have difficulty in the initial phase of using Portfolio for Jira. They try to start quickly, in connection with which arise many questions and difficulties and as a result th...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events