The PEAR package contains:
  * the PEAR installer, for creating, distributing
 and installing packages
  * the PEAR_Exception PHP5 error handling mechanism
  * the PEAR_ErrorStack advanced error handling mechanism
  * the PEAR_Error error handling mechanism
  * the OS_Guess class for retrieving info about the OS
 where PHP is running on
  * the System class for quick handling of common operations
 with files and directories
  * the PEAR base class
 Features in a nutshell:
  * full support for channels
  * pre-download dependency validation
  * new package.xml 2.0 format allows tremendous flexibility while maintaining
 BC
  * support for optional dependency groups and limited support for
 sub-packaging
  * robust dependency support
  * full dependency validation on uninstall
  * remote install for hosts with only ftp access - no more problems with
 restricted host installation
  * full support for mirroring
  * support for bundling several packages into a single tarball
  * support for static dependencies on a url-based package
  * support for custom file roles and installation tasks