I'm new to FHIR and resources.
Rules contain 0 to * conditions and 1 to * actions. All conditions are connected with the 'and'-Operator. If all conditions are met, all actions shall be performed.
It sounds like what you're trying to do is decision support. Look at look at http://hl7.org/fhir/2016sep/decisionsupportservicemodule.html. If you're thinking more about protocols, look at http://hl7.org/fhir/2016sep/plandefinition.html