This distinction was important in that such contextual substitutions occurred at rendering time, without any changes to the source character string. Thus they had no impact on editing or searching of the text. PostScript Type 1 font files have one to one mapping only, and as ligatures are many to one mappings, they can not be inserted into the composition without changing the source character string, for instance, the ligature ffi is placed at the position of capital Y in Adobe font products, and "Adobe Offices" is composed by typing "Adobe O" <change font> "Y" <change font> "ces". In the layout the character string is broken, and in PDF made from streamed PostScript the characters f+f+i can only be reconstructed, if the name of the glyph follows a glyph naming list.