type A: <"description">
    a int (1..1) <"A">

type B extending A: <"description">
    b int (1..1) <"B">

type C extending A: <"description">
    c int (1..1) <"C">

type D extending B: <"description">
    d int (1..1) <"D">

type F extending B: <"description">
    f int (1..1) <"F">

type G extending C: <"description">
    g int (1..1) <"G">

type H extending C: <"description">
    h int (1..1) <"H">