You can store anything, it works the same way as an ini file, using a key/value format. The only thing you are missing is the sections of settings, which you can handle by naming your keys appropriately. And of course, this is a binary file so no text editor editing.
PHP Code:
nvault_set( vault , "setting" , "value" )
nvault_get( vault , "setting" , szValue , charsmax( szValue )
OR
iVal = nvault_get( vault , "setting" )