What symbols are used in Sizwe Banzi Is Dead that develop the plot of the play?

The South African passbook is the most overt object discussed in the play Sizwe Banzi Is Dead, by Athol Fugard, John Kani, and Winston Ntshona, and its power as a symbol of oppression is central to the development of the plot of the play.
Black South Africans struggle against the bleak and violent oppression of apartheid in the 1970s. Each black person in the country is issued a passbook, and the exacting symbolism of the passbook is dehumanizing: inside each passbook, the name of its owner is equated to and replaced with a number. The racist symbolism of the passport is to erase identity itself.
This symbolism is talked about by the characters of the play, who are all too aware of its power and terror. The play is a dialectic between its three characters about the nature of the symbolism of the passport, as well as the nature of the symbolism of the photography that is used in the passbook—the photo of the person to whom the passbook belongs.
Co-playwright Athol Fugard states that he is drawn to the specifics rather than the universal. “I think it was Camus who spoke about the ‘truth the hand can touch,’ ” Fugard says. And beyond the dialectic, the character Buntu performs “surgery” on passbooks to literally change identities. The photograph of one man is swapped for the photograph of another man. As the play unfolds, Sizwe Banzi struggles and finally decides it is worth the risk to “die” and adopt the identity of another man—another passbook, in which his photograph is grafted to the name and number identity of someone else.
The racist symbols of oppression can be changed, but at what cost? “Robert . . . Sizwe . . . I’m all mixed up. Who am I?” says Sizwe as he adopts another identity. The cost of freedom can be terrible in a society that uses objects as symbols and carriers of oppression.