Apple Installer bundle-style package script variables as a comment block

BundlePackageScriptVariablesCommentBlock

# http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/SoftwareDistribution/Install_Operations/Install_Operations.html#//apple_ref/doc/uid/10000145i-CH14-SW1
# Arguments
# $1: Full path to the installation package the Installer application is processing.
# $2: Full path to the installation destination.
# $3: Installation volume (or mountpoint) to receive the payload.
# $4: The root directory for the system.
# Environment variables
# $SCRIPT_NAME: Filename of the operation executable.
# $PACKAGE_PATH: Full path to the installation package. Same as $1.
# $INSTALLER_TEMP: Scratch directory used by Installer to place its temporary work files. Install operations may use this area for their temporary work, too, but must not overwrite any Installer files. The Installer application erases this directory at the end of the install.
# $RECEIPT_PATH: Full path to a temporary directory containing the operation executable. This is a subdirectory of $INSTALLER_TEMP. This location may vary between installs. The executable can use this path to locate other files in the package.