PyCharm File Template Velocity Support

In the help for PyCharm File Template Variables (and at https://www.jetbrains.com/help/pycharm/2016.1/file-template-variables.html) is the following statement.

"If the value of a variable is not defined in the template, PyCharm will ask you to specify it when the template is applied."

I interpret this to mean that if I define a variable, such as ${Description}, that does not have a predefined value that PyCharm will ask me for the value when i create a file with this in the template.  Is this interpretation incorrect?

Since my goal is to have PyCharm ask me for the value to be placed where the variable is defined, how can I accomplish this?