Data stewards enforce policies, and functional data managers implement the policies and manage day-to-day quality. Data stewards regularly assess classification criteria and test compliance to prevent security issues resulting from data aggregation.
Sources:
CNSSI 4009-2022

  A designated group or individual assigned to prepare data collection plans, collect and store program performance data, and analyze and report data in response to performance information requests.
Sources:
CNSSI 4009-2022 from NSA/CSS Policy 1-50

  Data stewards are legally accountable across the data lifecycle on behalf of the originating element for: a) establishing protection, sharing and governance guidelines for data and datasets within an assigned subject area; b) maintaining data names, business definitions, data integrity rules, and domain values within an assigned subject area; c) compliance with legal and policy requirements and conformance to internal and IC data policies and data standards; d) ensuring application of appropriate security controls; e) analyzing and improving data quality; and f) identifying and resolving related issues.
Sources:
CNSSI 4009-2022 from IC Data Management Lexicon