The sign is the part of the symbol perceptible by the senses.
3.321 Two different symbols can therefore have the sign (the written sign or the sound sign) in common - they then signify in different ways.
3.322 It can never indicate the common characteristic of two objects that we symbolize them with the same signs but by different methods of symbolizing. For the sign is arbitrary. We could therefore equally well choose two different signs and where then would be what was common in the symbolization?
3.323 In the language of everyday life it very often happens that the same word signifies in two different ways - and therefore belongs to two different symbols - or that two words, which signify in different ways, are apparently applied in the same way in the proposition.
Thus the word "is" appears as the copula, as the sign of equality, and as the expression of existence; "to exist" as an intransitive verb like "to go"; "identical" as an adjective; we speak of something but also of the fact of something happening.
(In the proposition "Green is green" - where the first word is a proper name as the last an adjective - these words have not merely different meanings but they are different symbols.)
3.324 Thus there easily arise the most fundamental confusions (of which the whole of philosophy is full).
3.325 In order to avoid these errors, we must employ a symbolism which excludes them, by not applying the same sign in different symbols and by not applying signs in the same way which signify in different ways. A symbolism, that is to say, which obeys the rules of logical grammar - of logical syntax.
(The logical symbolism of Frege and Russell is such a language, which, however, does still not exclude all errors.)
3.326 In order to recognize the symbol in the sign we must consider the significant use.
3.327 The sign determines a logical form only together with its logical syntactic application.
3.328 If a sign is not necessary then it is meaningless. That is the meaning of Occam's razor.
(If everything in the symbolism works as though a sign had meaning, then it has meaning.)