The NUL character in the ASCII character set was originally ment to be treated as a NOP, a character to be ignored. This would be useful on paper tapes where additional information had to be added in between existing information. However, some printing devices had the NUL implemented as a wite space instead. Later on, the importance of the null character increased significantly when it was defined as the string terminator in the C programming language. It made it possible to define strings of infinite length in programming languages. Until then most languages like Pascal defined a string as a length indicator, followed by an array that contained the characters.