Company-specific standards which are developed internally and apply to the whole supply chain of a company (e.g. Tesco's Nature's Choice, Wal-Mart’s Sustainability Product Index).
Consortia standards which are often developed by a sector-specific professional consortium (ie. GlobalGAP, Responsible Care initiative in the chemical industry)
Partnership standards developed by a coalition of business, civil society and sometime governmental representatives (e.g. the Global Reporting Initiative (GRI) sustainability reporting guidelines)
Civil society standards established as an initiative by an non-profit organization usually as a response to concerns over social and environmental issues (e.g. SA8000 of Social Accountability International, Forest Stewardship Council).
Private standards are voluntary standards, which become de facto mandatory in trade relationships