System architecture margins for the ilities

Paper in proceeding, 2026

Engineers often treat margins as buffers or excesses which are added to parameters, appearing much later in the product development process. However, many key lifecycle properties e.g., reliability stem from early architectural decisions which either need margins for their enablement or create margins in the process. These buffers are rarely treated explicitly as margins. This paper argues that there is a clear relationship between architectural objectives and margins and explores four examples of ilities providing a new perspective for reasoning about ilities in early system design.