• Best Practices, Tips and Tricks for Implementing XDS (Extensible Data Security) policies (https://blogs.msdn.microsoft.com/daxserver/2013/06/26/best-practices-tips-and-tricks-for-implementing-xds-extensible-data-security-policies/)
• Security architecture (https://docs.microsoft.com/en-us/dynamics365/operations/dev-itpro/sysadmin/security-architecture)
• Security Policies Properties for AX 2012 (https://msdn.microsoft.com/en-us/library/gg731857.aspx)

This is still relevant in Dynamics 365 for Operations