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.

* If you want to see (and log) tons of debugging output, you can use 
  PM_DEBUG="true" to have the script log each action as it performs it.

* If you want to see how long pm-utils takes to run hooks. you can use
  PM_PROFILE="true" to log timing information on how long each hook takes
  and how long running the hooks takes overall.

* 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.

* To override the usual quirk filtering (for kernel modesetting, binary drivers,
  and exotic hardware), pass --quirk-test along with any other quirks you want
  to try.  This may make your system crash in new and exciting ways by
  conflicting with the kernel when suspending or resuming, but is very useful
  for debugging.  You have been warned.

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. The sole exception is
  the video quirk database handler, which would be a couple of orders of 
  magnitude slower when written in POSIX sh, due to how heavily it relies on 
  bash native regular expression support.