Key words are separated either by a space or a comma. A case makes no difference. 
      With “AND” search only data with all of the key words may be found. “OR” search allows all data with at least one key word to be found. In any search mode “+” in front of the key word means that the files being found should contain this key word. To delete a word from search “-“ is inserted in front of the word. “!” behind the key word means that only words meeting the request precisely are to be found.