Agreement with the truthpossibilities can be expressed by coordinating with them in the scheme the mark "T" (true).
Absence of this mark means disagreement.
4.431
The expression of the agreement and disagreement with the truthpossibilities of the elementary propositions expresses the truthconditions of the proposition.
The proposition is the expression of its truthconditions.
(Frege has therefore quite rightly put them at the beginning, as explaining the signs of his logical symbolism.
Only Frege's explanation of the truthconcept is false: if "the true" and "the false" were real objects and the arguments in ~p, etc.,
then the sense of ~p would by no means be determined by Frege's determination.)
