The problem is the SEC, it does not clearly define "shell" to a degree of certainty. You will find that many securities lawyers cannot provide a generalized opinion as to what is a shell by SEC definition. Each security has to be assessed as to what it really is and if it fits the definition. I have read that most securities lawyers error on the side of a shell for that reason, because if it cannot clearly define itself and rides the grey area it is best to be defined as a shell.
However we know that is the opposite here in the OTC, it is much better to act as if it is not a shell to be able to apply exemptions for sale of shares.
For example what is no or nominal operations, producing a sale a year or a sale every 6 years.....
What is a nominal asset, $3, $30, $300, $3000 or $30,000..
The SEC essentially left it loose for their own interpretation as to what is a shell. Why? I suppose for one that it prevents a shell from just reporting enough operations or assets to be defined as not a shell.