What are the various data types permitted in Appian rule input
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AFAIK if it's a datatype (see https://docs.appian.com/suite/help/21.4/Appian_Data_Types.html) then it's a candidate for a rule input. What is the question behind your question? What is it you really want to know?
I want to know that, does Appian rule inputs accepts a handful of datatypes.
Also, is there any restriction where a certain datatype cannot be used in rule inputs
No restrictions AFAIK. Why, are you seeing a situation where you can't reference a datatype?