If they have been incorporated in mainland China, they trade as ADRs of H Shares.
If they have been incorporated in Hong Kong, they trade as ADRs of Red chips.
If they have been incorporated in Nevada, Delaware or Florida, they might have originated as reverse mergers.
However, the term N-Shares may only refer to private sector Chinese companies incorporated outside China, which excludes ADRs of H Shares or Red chips.
As of December 2010, the SEC is investigating frauds by publicly traded Chinese companies.