odern engineering and business practices in the automotive domain use massive subcontracting of SW/HW components and subsystems. We present a preliminary research towards applying a quantitative, compositional safety assurance approach based on the ISO 26262 concept of SEooC (Safety Element out of Context). In this approach a component must be evaluated against 'assumed' operational context conditions in a quantitative manner (based on compatibility/gap analysis), instead of using inspections. Once the component becomes part of a specific system in an actual operational context, the evaluation is optimised by comparing assumed context conditions against actual context conditions. We propose a classification to organize information about assumptions and guarantees and outline a procedure to systematically manage their specification, validation and gap analysis.