3.34 A proposition possesses essential and accidental features.

The accidental are those features that come from the particular way of producing the propositional sign. The essential are those which alone enable the proposition to express its sense.

The accidental features would then seem to be what it sounds like, if spoken, or how it looks, if written, etc. The essential would belong not to the sentence but to the proposition. What could those be? Not its sense, since they are said to be whatever it is that enables the proposition/sentence to express its sense. They are presented as non-physical sense-making powers or prerequisites. Is this metaphysics, or have we strayed into nonsense?