Perforce Jam was an open-source build system developed by Christopher Seiwald of Perforce Software. It was used as a replacement for make. Its primary feature was its ability to express build patterns in an imperative language which supported structured namespaces (similar to Pascal records) and simple lists. Jam could be used with autoconf, although it was often not necessary because of Jam's portability features. Perforce Jam ran on Unix (including many clones), OpenVMS, Windows NT (including Windows 2000 and Windows XP), Mac OS, and BeOS. It was also possible to configure it to work on Windows 9x using MinGW or Cygwin.