I don't think it really matters. I think Purina is trying to say that the blocks are not meant for caged birds. We use them as a supplement in the barn in the dead of winter when there is no pasture available for our flock.
According to the label I have in front of me...
Purina Flock Block -...
We have a two-tier wire-basket hanging planter that is made of heavy gauge steel. We found it at a clearance sale at a local nursery for $1.50 a few years ago.
We hang it from a beam in the barn on a bungie cord. We fill the lower basket with veggies, hay or fruit (a quartered head of cabbage...