What is meant by a Companion's fatwa and what relates to it?

The intent behind a Companion's fatwa is their saying and their madhhab (school of thought). If there is no room for personal opinion in it, then it is considered as if it were a Marfu' (elevated) Hadith, takes precedence over qiyas (analogical reasoning), and specifies a general text. If it is a matter where personal opinion is permissible, and it became widespread without any apparent opposition, then it is a silent consensus (Ijma' Sukuti). However, if opposition to it is known, then it is not acted upon except after re-evaluation and preferring one view over another. If it did not become widespread, some say it is a proof because the Companion witnessed the revelation (Tanzil), while others say it is not a proof. Some also say that the proof lies in the fatwas of the four Rightly Guided Caliphs, and others say it is only in the sayings of Abu Bakr and Umar.