for I := 1 step 1 until 10 do (A[I], for J := 1
step 1 until 20 do B[I,J])
is equivalent to the list
A[1], B[1,1], B[1,2], ..., B[1,20],
A[2], B[2,1], B[2,2], ..., B[2,20],
....................................
A[10], B[10,1], B[10,2], ..., B[10,20] .
A list may be given a name through a list declaration. A list declaration has the form
list identifier := list .
Examples are: