Lotus Notes is very wary of its database files, also known as .NSF-files, becoming corrupted. So much so, in fact that IBM has created a whole class of files designed to recreate these files. This class of files is called .NTF files.
NSF is an abbreviation of Network Storage Facility, and each, or at any rate most, NSF file has a corresponding NTF, or template file. Simply put, when, oh let’s say your bookmarks.nsf file gets corrupted (as they seemingly invariably do), you simply rename it, restart Notes, and Bob’s your uncle; the problem is no more.