[Note that the word “Things” is here used with a special meaning, as explained at [p. 23].]
A Proposition, containing only one of the Letters used as Symbols for Attributes, is said to be ‘Uniliteral’.
[For example, “Some x exist”, “No y′ exist”, &c.]
A Proposition, containing two Letters, is said to be ‘Biliteral’.
[For example, “Some xy′ exist”, “No x′ are y”, &c.]
A Proposition is said to be ‘in terms of’ the Letters it contains, whether with or without accents.
[Thus, “Some xy′ exist”, “No x′ are y”, &c., are said to be in terms of x and y.]