I asked PTSC how many re exams are possible , their reply posted.

Hello Bob,
The USPTO is entertaining a re-examination request for the '336 patent, something it has done in the past and for which has even recently issued a Notice of Intent to Recertify. Unfortunately, there is no definitive timeline or event that precludes a patent from being subject to re-examination requests. Presumably the basis for such requests is finite and the opportunity for challenges will be exhausted, but it is difficult to identify when that will occur.

Thank you for your words of encouragement and support.

Sincerely,
PTSC Investor Relations