3.0 Agent Technical Issues
As a website owner, the P3P standard is pretty set. However, the companies developing the agents (browsers) have their own methods for implementing the specification.

A. Possibly the biggest issue in the P3P implementation is how Microsoft included the compact policy logic in IE6.

The P3P specification reads, "Compact policies are summarized P3P policies that provide hints to user agents to enable the user agent to make quick, synchronous decisions about applying policy. Compact policies are a performance optimization that is OPTIONAL for either user agents or servers. User agents that are unable to obtain enough information from a compact policy to make a decision according to a user's preferences SHOULD fetch the full policy."

Internet Explorer 6.0 does not conform to this standard. For IE6, if there is no compact policy, the browser assumes there is no policy.