What is an example of symbolism in the novel, A Wish in the Dark?

Each prisoner of Namwon and the other prisons has a permanent tattoo that symbolizes they are a prisoner. The tattoo is adjusted once the person is lawfully released, but the tattoo remains a symbol that the person is a criminal. That means everyone, including potential employers, has this information at a glance. Pong's tattoo is covered by the strings Father Cham gives him.