In the talk will be considered what the purpose indicators are and why they are important in the development of IS. We will discuss the classification and typification of indicators: functional, technological and technical. Will select those that are identified during the survey, and those that depend on other factors (and specify from which ones). How to collect and for what to use the purpose indicators at different stages of analyst's work. Besides, we will talk about whether purpose indicators are always non-functional requirements and vice versa. For each category of indicators, the properties, the stage of definition and refinement, the intended use and placement in the documentation will be provided.