This document defines the requirements to perform functional analysis and the information output of that analysis. It applies to all types and combinations of space systems, projects and products. It also applies to project phases 0, A, B and C and at all levels. When viewed from the perspective of a specific project context, the requirements defined in this document should be tailored to match the genuine requirements of a particular profile and circumstances of a project. NOTE Tailoring is a process by which individual requirements of specifications, standards and related documents are evaluated and made applicable to a specific project by selection, and in some exceptional cases, modification of existing or addition of new requirements.