The .file and .disk directives use parameter maps to describe their parameters. These are square brackets with comma separated parameters:
[name="Bob", age=27, useGlasses=false, wearsTshirt]
You can assign any type of value (strings, numbers, booleans, etc) to a parameter. Notice the last parameter has no assignment. This is a short notation for assigning the boolean value 'true' to the parameter ('wearsTshirt=true').