Hi ,
Each implementable SAP note ( that will have a correction instruction ) will be a part of a SP .
If your system is equal to or above that support pack the SAP Note is not applicable to you and cannot be implemented
If the version of the note changes and ( the new version is not applied yet applied in the system ) , it will be marked as an obselete version . In such cases using TXN SNOTE you can implement the note once again .This can be easily checked via txn SNOTE, download the latest note and click execute .
Thanks ,
Manu