To specify the REQ, D-IN, and D-OUT relations, SCR specifications use a set of tables.
Each table defines the value of a dependent variable (a mode class or controlled variable) as a
function. A table may be either a condition table or an event table. Typically, a condition table
describes the value of a controlled variable as a function of a mode class and a condition, whereas
an event table describes the value of a controlled variable as a function of a mode class and an
event. A mode transition table is a special case of an event table. Although many SCR tables use
modes to define the value of a variable, some SCR tables omit modes.