How many .usd* files I can enclose into a .usdz file for ARKit?

Say I have one .usdc file which references to other .usd files. Can I enclose the .usdc file and all other .usd files referenced by the .usdc file into one .usdz file?
How many .usd* files I can enclose into a .usdz file for ARKit?
 
 
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