There are various types of difference among signs and words. Here in this Standard Chinese Telegraph Table. The difference between codes can be numerical, digital or the most considered: literal. Now the least cared difference -- physical distance (in 3-dimensional .i.e., x, y and z0 between the numbers marked in Domestic Amnesia are measured in mm. 

Chinese code for telegraph probably is one of the most forgotten "chinese" languages. It seems meaningless in our daily life even though Chinese Hong Kong residents always keep it as their names on their Identity Cards.