S="a string with a quote character <<"'>> "  
S='a long string  ... /// \sleftarrow{\normalfont \verb+...+ used to {continue} on next line }
   using continuation ' 
S=['A','string';'2x2','matrix'] /// \sleftarrow{\normalfont a string matrix }
length(S) /// \sleftarrow{\normalfont length of each string of \verb+S+ in a matrix}