Effect:

The effect is like executing the conditional assignment

   if(msk [  ])

    dst [   [  ], ...,
                
[  ]] = src [  ]

for every tuple, , of global subscripts of the source array. These assignments are executed in an undefined order. Here denotest the rth subscript array. If subs [r] is null, the value of the expression [ ] in the left-hand-side of the assignment is defined to be .