You have questions on Policy deprecation warnings
When installing policy, a policy deprecation warning will be displayed if CPL syntax is used that has been replaced in the OS version you are currently running (or trying to upgrade to). In some versions both syntaxes will compile and the warnings exist only to notify you that you are using deprecated syntax. However, in some versions the older syntax has been abandoned and you are required to correct the policy before it will successfully install and compile. This is true when upgrading from SG3 to SG4.