Unknown writing

The Unknown Writing, also called Titan Writing is an unintelligible writing or code shown on a can of herring in Castle Utgard. So far, the series has provided very little information on its origin, use, or true nature, but it is known that the writing can be read by at least Ymir though it is possible there are more people capable of reading it.

Form
The Unknown Writing appears as block-like code but contains some inconsistencies in its multiple appearances. In its first appearance in which the series directly reveals its existence, though still nameless currently, the writing appears partially almost like Japanese hiragana or katakana. Upon closer look, the characters are partially covered in shadow but one clear character can be seen, appearing like the letter Z or hiragana's ko syllable.

Appearances
During Ymir and Reiner's conversation in Castle Utgard, Ymir reads the mysterious writing on a can. However, the conversation is cut short by the incoming attack of Titans on the castle and Reiner states that he cannot read the writing at all.