End-user customization and debugging:

* If a particular hook is causing problems on your system, you can disable it
  using the HOOK_BLACKLIST environment variable by creating a file in 
  /etc/pm/config.d and adding the line:
  HOOK_BLACKLIST="hookname 99another-hook"

* If a parameter (or lack thereof) passed to pm-suspend and friends is causing
  problems, or you need to debug the suspend/resume process to work out what 
  quirks are causing problems, you can use the ADD_PARAMETERS and 
  DROP_PARAMETERS environment variables.  To do this, create a file in 
  /etc/pm/config.d, and add the following lines to it:
  ADD_PARAMETERS="--parameter-to-add --another-parameter"
  DROP_PARAMETERS="--parameter-to-drop --another-parameter-to-drop"

  If you want to drop all parameters (for testing purposes, or to work around 
  bugs in HAL), you can use DROP_PARAMETERS="all"

* If you suspect that a kernel module is preventing you from being
  able to suspend and resume, you can use the SUSPEND_MODULES
  environment variable to have that module removed when the system
  suspends and reloaded when the system wakes up.

* If your clock drifts across a sleep/wake cycle, you can use 
  NEED_CLOCK_SYNC="true" to force pm-utils to synchronize clocks.
  This is a change in the default behaviour of pm-utils -- 1.2.2.1 and earlier
  always synchronized clocks, but doing so is slow and most hardware stays in
  sync without assistance.

* To find out what parameters can be passed to pm-suspend and friends, run them
  with '--help' as the first parameter as root.  This will print out the 
  options that it supports and which hooks or modules handle those options.

Significant conceptual changes from pm-utils 0.99.x and earlier:

* Do not rely on the internals of hooks when configuring or customizing
  pm-utils.  Conceptually, hooks are black boxes from the point of view
  of the pm-utils core code, and there is no guarantee that the implementation
  of a given hook will not change from pm-utils revision to pm-utils revision.

* The preferred method of modifying the behaviour of a hook is to modify the
  ADD_PARAMETERS and DROP_PARAMETERS to change the global parameters available
  to each hook.

* All scripts created and maintained by the pm-utils are POSIX/SuS compliant.
  Any modification or new script should be POSIX compliant and work as intended
  using dash and posh before you submit a patch upstream.