Dear Harvey and Karl, I can only say again to both of you – thank you. I have taken your comments on board and looked up the works you refer to. I will read the articles and buy the books and then come back to you – hopefully wiser and more knowledgeable – with more questions. Good – night Best wishes Cherryl -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.7.1/347 - Release Date: 24/05/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.7.1/347 - Release Date: 24/05/2006