Mark Logic basically makes an XML DBMS â" confusingly called Marklogic without a space - optimized for document processing (including text search). Mark Logicâs main market is custom publishing â" assembling documents on the fly, whether based on search or some other starting point. Airlines put Marklogic to an interesting use: They create âelectronic flight bags.â Apparently, flight crews typically carry a whole satchel of documents (flight bags) onto a plane, the precise contents of which freq