The files in this directory are evaluated in C sort order. These
files can be provided by individual packages outside of pm-utils.
If a global configuration variable is set, the value set to will be
appended to the previous value. If any other variable is set, it
will be ignored. The syntax is simply: VAR_NAME = value. See the
CONFIGURATION VARIABLES section for valid variables defined by
pm-utils. External packages can define others, see their respective
documentation for more information.
The hooks for the power state are placed in
distribution / package provided hooks
hooks added by the system administrator
Hooks in /etc/pm/ take precedence over those in /usr/lib/pm-utils/, so the system administrator can override the defaults provided by the distribution.
For instance check this link