Source code has comments to help Java programmers recall or determine how a program works. (Comments are ignored by the computer, and they are not accessible to ordinary users.) The initial comment block includes the fi le name as a continuous reminder to the programmer. It contains program authors, for help and reference. It may include date and version number to identify context. It includes a short description to facilitate rapid understanding. Punctuation comments like // end class help keep a reader oriented. Special comments identify variables and annotate obscure formulas.