The actor's letters form the 'basis' of the biography. [=the biography is based on the actor's letters; the most important information in the biography comes from the actor's letters]
This principle forms the 'basis' [='base', 'foundation'] of the country's economic policies and will provide a firm 'basis' for future development.
These stories have very little 'basis' [='foundation'] in fact/reality. [=these stories are not based on or supported by facts/reality]
(..) Good. Good. So, soldier... ...what the hell are you doing here? -What did we find down there? -You'll be briefed... -...on a need-to-know basis. -Well, I need to know. Because my men died down in that hole. What did we find down there? We found a solution, Connor, (..)2009 Terminator Salvation