It is true. I have a lot of data (pairs: what to change w/ what). And in example i missed () to organize it to $1. -- All this i know, what here i do not know is the index used by PERL. -- As my data is somewhat big, i would like to use the error message i get -- to easily find the place in the data, that does not have in example () but has in exchange $1. So, from which is it counted?