-Always sends locationnum, action and any fields specified in the 'Include fields'
-export option. Action 'package' also sends pkgnum and old_pkgnum (because location
-changes usually instigate a pkgnum change.) Action 'location' only sends on replace
-if one of the specified fields changed. Leave a URL blank to skip that action.
+Leave a URL blank to skip that action.
+Always sends locationnum, action, and fields specified in the export options.
+Action 'package' also sends pkgnum and change_pkgnum (the previous pkgnum,
+because location changes usually instigate a pkgnum change.)
+Simple field values can be selected in 'Include fields', and more complex
+values can be specified in the data field options as perl code using vars
+$cust_location, $cust_main and (where relevant) $cust_pkg.
+Action 'location' only sends on update if a specified field changed.
+Note that scheduled future package changes are currently sent when the change is scheduled
+(this may not be the case in future versions of this export.)