Микроконтроллеры PIC

можно ли записывать данные во флэш(pic18F46k22) не стирая блок. У меня не получилось. если нельзя то почему и зачем тогда вот это:

Note: The default value of the holding registers on device Resets and after write operations is FFh. A write of FFh to a holding register does not modify that byte. This means that individual bytes of program memory may be modified, provided that the change does not attempt to change any bit from a ‘0’ to a ‘1’. When modifying individual bytes, it is not necessary to load all holding registers before executing a long write operation.