This is quite a good site for detailing what the different entries are on BMD certificates and some 'unusual' events that can occur (including getting the gender of a child wrong on the Birth certificate!)
http://www.dixons.clara.co.uk/Certificates/indexbd.htm
General help on BMD certificates
General help on BMD certificates
Researching FLANAGAN, BLAIR, COLERIDGE, HOLDEN & HUMPHREYS
Member # 8595
Member # 8595