AI governance has been increasingly preeminent in digital world which presents a practical challenge of combining technical digital implementation with legal governance in real world. This work proposes a strategical bridging framework between AI governance policies and technologies on the fundamental content expression modals of data, information and knowledge, and crossing modals processing of DIKW content/resources through formalization abstract or intangible policies and their interactions as concrete technical tangible executions of modal transformations, essential computation and reasoning. The essential content oriented formalization, computation and reasoning of features, policies and associations bridging legal pursue and technical details is unified based our proposed existence computation and relationship defined everything of semantics mechanisms, which we further proposed as essence computation and reasoning for multiple modal and cross modal content. We demonstrate the feasibility and effectiveness of our essential content oriented multiple modals analysis and modeling through construction of a systemic privacy protection framework in the background of the whole process of perception, storage, transition and processing of user generated content in virtual communities. This solution framework seamlessly integrates originally discrete policies and demands on fairness, personal security, financial security, peace and quiet, autonomy, integrity against commodification and reputation at the technical execution level in terms of specific activities and concrete actions inside and cross data modal, information modal and knowledge modal.