Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:[57] conception of layered modular architectures, we theorize digital platforms as encapsulating five distinct and interlinked platform layers: (1) device; (2) system; (3) network; (4) service, and; (5) content.
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