In this type of ordering, one realization has precedence over another. As the two realizations are alternatives, in an OR relationship, there is no temporal ordering as in the case of the AND relationship.
In the case of realizational formulae, precedence ordering always involves formulae with the same symbol at the left of the slash (/), and these rules are alternatives; i.e., they are in an either-or relationship to one another. The single symbol at the left corresponds to the single line above the downward ordered OR node in compact relational network notation. A single formula is used for each realizate, with a separate subformula (on a separate line) for each environment and realization. The subformulas are listed in the order of precedence, and since this is a precedence ordering of alternatives, they all occupy the same realizational level (stratum). Each subformula is allowed to operate only if the conditioning environment(s) of what precedes it does not apply.
- Lamb, Sydney M., Language and Reality: Selected Writings of Sydney Lamb, Continuum, 2004.