Key of the answer in the form's values (and in c.state with flatten).
Letters, digits and _, starting with a letter or _ (/^[A-Za-z_][A-Za-z0-9_]*$/).
Short label shown next to the input (native) or used as the question (degraded).
OptionalrequiredWhether an answer is mandatory. Default true (false for optin).
OptionalhelperExtra hint under the input (native) / appended to the question (degraded).
OptionalpromptDegraded mode only: full question text instead of label (+ helper).
OptionalerrorError message used when an answer for this field is invalid (overrides the built-in ones).
OptionalminMinimum number of picks (default 1 when required, else 0).
OptionalmaxMaximum number of picks (default: all).
Pick several options (
c.stategets an array of option KEYS, in option order).