A single written sign, and the settled nature of a person. Both are what a thing is recognisable by.

That which turns a thing into another form for carrying or storing. Encoding is reversible; that is what separates it from translation.

A pattern describing which strings are meant. Powerful, terse, and the commonest place a subtle error hides.

A mark that stands for something by agreement rather than resemblance. A symbol must be learned; an image need only be seen.