I'm definitely not the best guy to answer questions but if you are searching for a string where 2 letters - underscore - 4 numbers - 1 letter - 2 numbers then:


Find=[A-Z]{2}_[0-9]{4,}[A-Z]{1,}[0-9]{2}


is the naming convention always the same? (PK_2314K16)


Best to post a sample of what you are looking for and what to replace it with.