Many search engines used in portals are optimized to retrieve predefined, specific and precise specifications
Now I know this is not the most exciting topic, but it is worthwhile because the role of taxonomy is becoming increasingly important to the complete search experience as well as the automatic classification of documents in various applications (see also the footnote)
Optionally, include all (hidden) meta-information in your archiving . Allow Federated search to your archives from within MS-SharePoint