I derived certain attributes that each RE approach has in common.
Firstly, a RE approach consists of a certain analysis technique.
Secondly, it uses a special notation to make it standardized and applicable for each analyst.
Thirdly, it follows a fundamental principle to achieve a certain goal.
Fourthly, there exists not only advantages but also disadvantages, making a RE methodology more or less appropriate for a modeling scenario.
CS510 - Software Requirements and Specifications