extensible data security (XDS) framework in AX 2012

The extensible data security framework is a powerful new feature in Microsoft Dynamics AX 2012 that has been made available to developers and customers to address rich data security policy scenarios. It enables developers and administrators to secure data in shared tables such that users have access to only the part of the table that is allowed by the enforced policy. This feature can be used in conjunction with role-based security (also supported in Microsoft Dynamics AX 2012) to provide more comprehensive security than was possible in the past.

Data Security policy concepts

When developing a data security policy, you need to become familiar with several concepts, such as constrained tables, primary tables, policy queries, and context

constrained tables	A constrained table is the table or tables in a given security policy from which data is filtered or secured, based on the associated policy query.
primary tables	A primary table is used to secure the content of the related constrained table.
policy queries	A policy query is used to secure the constrained tables specified in a given extensible data security policy.
context	A policy context is a piece of information that controls the circumstances under which a given policy is considered to be applicable. If this context is not set, then the policy, even if enabled, is not enforced.

The white paper published by Microsoft which contains complete information of the XDS framework along with a walk though.