Name the Conditional ....

Just stumbled across your conditionals section - excellent ! . One of the clearest explanations I've seen of a vast and confusing topic.
I'm interested in your opinions on the following sentence:
If you have any questions, just ask.
How would you classify this ? Zero ? First ? Mixed ? Imperatives seem to make the distinctions a bit murky ... any feedback would be greatly appreciated.
Many thanks

[Tdol]

The imperative is generally thought of as a first conditional, because it doesn't refer to a fact or something that's always the case. In your example, the imperative covers any number of occasions, but it still doesn't fit the zero pattern:

If they have questions, they ask- description of the situation
If you have any questions, just ask- creating or altering the situation