Other letters found as graffiti include frequent probable initials, sometimes accompanied by a date. Not all single or paired/triple letters necessarily represent initials though, and numbers may also have special significance.
A fairly common find is a lone capital I with a central cross bar (sometimes slight). This particular form of the letter I can also be read as J (which in its latter form, is a fairly recent letter) and is believed to represent the name Jesus.
Other representations of the name Jesus include the Latin or Greek forms IH, IHC, IHS, XPS and JC .
The letters P, and R, are not uncommon in churches and houses, although their meanings as lone letters are not clear. P is often found near to the door of a church, suggesting an apotropaic function.
Reversed letters are commonly seen and are probably mainly due to illiteracy, although reversed, or inverted (upside down) words may have another significance, being found in magical charms.