Trustmark means indication that a product or service provider has met the requirements of the Identity Ecosystem, as determined by an accreditation authority. A trustmark can be a simple image, appearing with little variation across multiple organizations and contexts (Passive trustmark).
Alternatively, a mark can change based on some criteria (Active or Dynamic trustmark).
Source: http://oixuk.org/wp-content/uploads/2014/09/Trustmarks-paper-FINALv2.pdf