Consider a text file containing the German word (meaning 'for') in the ISO-8859-1 encoding (codice_1). This file is now opened with a text editor that thinks that the input is UTF-8. The first and last byte are valid UTF-8 encodings of ASCII, but the middle byte (codice_2) is not a valid byte in UTF-8. So, a text editor could replace this byte with the replacement character symbol to make a valid string of Unicode code points. The whole string now looks like this: "f�r".