On 4 June 2012 05:02, Dave Coventry <dgcoventry at gmail.com> wrote: > I'll pick through that and see how much I understand... It's a good idea to read this, if you'd like to understand some of it: http://www.bbc.co.uk/rd/pubs/whp/whp031.shtml It comes with nice examples in (mostly) plain English. Henry