Article 5 of most treaties deals with what will be considered to be a “permanent establishment” (PE). This is important because, if a person is doing business through a PE in another country, normally the tax will be retained by the country where there is a PE.
Paragraph 1 usually has a short broad definition. Paragraph 2 has pretty standard definitions. Such as the ones in the Azerbaijan treaty which indicate that a PE will include a place of management, a branch, an office or factory, workshop or mine.
The important word in paragraph 2 is “include”. It provides for additional possibilities. That means that there may be many other possibilities as well.