Long-term tourist visa (1 year or more)

I have a friend from Vancouver who would like to apply for a long-term tourist L, for up to a year or more with multiple entry. She will be traveling into and out of China as a tourist regularly, and doesn't want to keep applying for a new one every time she travels; she already has 3 previous ones in her passport. Which type would she apply for and what special requirements (if any) should she have.

Thanks in advance.