kimāste vahnirāhosvinnivṛtta ityevaṃ sandihyamānaḥ sadbhāvo yasya vastunas tattathā tac ca tadvastu ceti tattathā tasya bodha iti vigrahaḥ
The compound is to be analyzed as "[that which has] the cognition of that thing whose existence is being doubted [with questions] like 'Is the fire there or has it ceased?'"