category, 7
class combinators
    ? combinator, 13
    “at” combinator, 9
    bind, 9
    delegation, 9
    disjoint union, 51
    Memory1, 18
    Once combinator, 9
    OnLoc combinator, 41
    Output combinator, 8, 10
    parallel combinator, 8
    Prior combinator, 13
    recursive composition combinator, 13
    simple composition combinator, 9, 11
    SM1-class, 18
    until combinator, 22, 26
classes
    base class, 8
    main, 9
    parameterized class, 8

event class relation, 5

kind, 7

message, 7
    directed, 7

single-valued, 5