Tattoo

The Roman campers get tattoos for every year they've been at the camp, similar to the camp beads at Camp Half-Blood. The tattoos have lines on them that are similar to a bar code which symbolizes the marks of honor given to Roman soldiers after every battle. The tattoos can never come off. The lines are burned on top of the symbol of their parent.

SPQR stands for Senatus Populusque Romanus. Meaning: The senate (Senatus) and (que) People (Populus) of Rome (Romanus). It was used as an official signature of the government, such as on coins or documents, statues or dedications and also the standards.

Godly Symbols

 * Children of Jupiter are marked with an eagle.
 * Children of Neptune are marked with a trident.
 * Children of Apollo are marked with a lyre.
 * Children of Mars are marked with two crossed spears.
 * Children of Bellona are marked with a crossed sword and torch.
 * Children of Pluto are marked with a black glyph like a cross with curved arms and a head.

Usage
When a camper at Camp Jupiter is no longer on probatio and is accepted into the legion, they are branded with the initials SPQR, the symbol of their godly parent or ancestor (if they are a legacy, like Octavian) and lines underneath, showing their years of service to the Legion.