The byte_jump keyword allows rules to be written for length encoded protocols trivially. By having an option that reads the length of a portion of data, then skips that far forward in the packet, rules can be written that skip over specific portions of length-encoded protocols and perform detection in very specific locations.
The byte_jump option does this by reading some number of bytes, convert them to their numeric representation, move that many bytes forward and set a pointer for later detection. This pointer is known as the detect offset end pointer, or doe_ptr.
For a more detailed explanation, please read Section 3.9.5.