wo types of triadic relations can be described as follows:

1.  "o" is a variable name for the "object",
        an element of the "object domain" O.

2.  "s" is a variable name for the "sign",
        an element of the "sign domain" S.

3.  "i" is a variable name for the "interpretant sign",
        an element of the "interpretant domain" I.

4.  "j" is a variable name for the "interpretive agent",
        an element of the "agent domain" J.

It is tacitly understood in all of this business that an "agent"