There was a 7th that I had never hear of, the IMACalloutExtension. Curious, I began to investigate. The Extension implements the following methods:
public void BeginExportToCd(string connectTo, string user, string domain, string password)
public void EndExportToCd()
public void BeforeExportEntryToCd(string deltaEntryXml, string changedAttributes)
public void AfterExportEntryToCd(byte origAnchor, string origDN, string origDeltaEntryXml, byte newAnchor, string newDN, string failedDeltaEntryXml, string errorMessage)
The only documentation that I could find was within the interface definition itself. It appears that this extension was to be implemented using a new Management Agent of type "Callout" (or something similar) and gives the developer the ability to take action both before and after each entry export action, which could be extremely helpful. I haven't been able to find a roadmap for this feature, but it appears to be something we can look forward to in the future!