You can use the folowing signs before words :
Query can include words with any sign infront (but only one sign per word).
There mustn't be any space between sign and word and there must be space between words.
- words without sign infront : find all data that contains at least one such word
- wirds with + infront : data MUST contain all this words
- words with - infront : data MUST NOT contain any of these words