Value chain emissions fall under the "Scope 3" emissions category of the Greenhouse Gas Protocol.
For example, a company's purchased goods and services, transportation, business travel, and waste produced during operations are all examples of indirect emissions that are produced by resources that the company does not own or control but that it indirectly touches in its value chain.
The GHG protocol's technical guidance for estimating scope 3 emissions describes the entire spectrum of emission categories.