Contents should be an array. Fields are 'name', 'ci', 'count', 'type', 'subtype', 'text', and 'pt'/'ptRanges'. ptRanges is objects of 'pt' and 'count', so that you can generate LOTS of tokens of different sizes quickly.

Most symbols from the comprehensive rules text will work, as demonstrated below. You SHOULD do those in the ci and text fields. You can leave off things--name will default to subtype. Count can be 0, or you can add 'skip' as 'true' to skip things more easily (generally for ptRanges).