```
= LET(
n₁, ROWS(Schedule),
n₂, COLUMNS(Schedule)-1,
k, SEQUENCE(n₁*n₂,1,0),
i₁, 1+QUOTIENT(k,n₂),
i₂, 1+MOD(k,n₂),
material, INDEX(Schedule[#Headers], 1+i₂),
product, INDEX(Schedule, i₁, 1),
quantity, INDEX(Schedule, i₁, 1+i₂),
unpivotted, CHOOSE({1,2,3}, product, material, quantity),
FILTER(unpivotted, quantity>0) )
```