Relation R: (linear order)
R(a,a), R(a,b), R(a,c)
R(b,b), R(b, c)
R(c,c)
R(0,x) x = 0, a, b, c, 1
R(x,1) x = 0, a, b, c, 1

Orthosupplement:
0 a b c 1
0 c b a 1

Candidates to fill: (0, a), (0, b), (0, c), (0, 1)*, (a, a), (a, b), (a, c)*, (b, b)*