In Old and Middle English, the roles of the three words were different from their roles today. "The interrogative pronoun "hwā" 'who, what' had only singular forms and also only distinguished between non-neuter and neuter, the neuter nominative form being "hwæt."" Note that neuter and non-neuter refers to the grammatical gender system of the time, rather than the so-called natural gender system of today. A small holdover of this is the ability of relative (but not interrogative) "whose" to refer to non-persons (e.g., "the car whose door won't open").