.comp A {
    .decl Rel(x:number)
    Rel(1).
}

.comp B : A {
    .override Rel
    Rel(2).
}

.comp C : A {
    Rel(3).
}

.comp D : C {
    .override Rel
    Rel(4).
}

.comp E {
    .decl Rel(x:number) overridable
    .override Rel
    Rel(1).
}

.comp F {
    .decl Rel(x:number)
    .override Rel
    Rel(1).
}
