RBI has allowed investments by NRIs or Persons of Indian Origin
(PIOs) in the capital of an entity or a proporietary concern on a non-
repatriation basis. It is subject to that the firm or proprietary
concern has not engaged in any agricultural plantation or real estate
business, immovable property with a view to earning profit or earning
income.

For more such information:
http;//www.banknetindia.com/books/handbook.htm