The second half
On this page12
The construction clause
But this paragraph shall not be construed as authorizing any limitation on the size, shape, weight or mass, dimensions, or number of packages which may be used to enclose any commodity.
It is a limit on the authority, not on the packager
Which is an unusual thing to find in a statute a packaging catalog would read. Most provisions here tell a packager what to do; this one tells an agency what it may not do.
Size and shape are the obvious two
No standard made under this paragraph can require a particular capacity or a particular form.
Weight or mass is the third
Which for a powder is the declared quantity. So the paragraph expressly declines to set standard fill weights.
Dimensions is the fourth
Height, diameter, footprint. We publish diameter on 152 of these containers and height on 161, and nothing made under this paragraph can constrain either.
And number of packages is the fifth
Which reaches the thing the concentrates property found a limit measured in: there, a federal figure was expressed per container. Here the paragraph declines any power over how many packages are used.
So three properties in this library now sit at three points
The cider rule restricts the fill to a list. The concentrates figure counts containers. This paragraph forecloses both kinds of limit for the commodities it covers.
Which is why the commodity matters more than the principle
There is no general federal stance on whether a container may be regulated. It depends entirely on which scheme reaches the product.
And a supplement sits in several at once
Deemed a food, labeled under the supplement rules, and a consumer commodity for the purposes of this statute.
And the clause is a construction rule, not a saving clause
Shall not be construed as authorizing. So it directs how the paragraph is read rather than carving an exception out of something it would otherwise reach.
The practical reading
Do not assume a container size is constrained, and do not assume it is free. Find the scheme first.