For example:
- not set / empty (e.g. comes in handy when setting a custom dimension only on certain behaviour, then it would be great to be able to segment users that don't have this certain custom dimension)
- it would be great to be able to define a specific variable type for custom dimensions, e.g. string/number/boolean/date - then the comparison operator could offer context sensitive comparison options. Mixpanel does this quite well:
