Thanks Macropod,
There is an awful lot of information in the links so i wont close this thread just yet... I may have to pick your brain a bit more...
Cheers.

Hi Again,
I have read, and re-read the instructions in the 2 provided links.... as i said earlier, a ton of information. The thing is that these 2 links refer to word 07 and i'm using word 2010. I cant find how to add the document property "InvNum" because File, Properties, Custom does not exist (in that word 10 anyway) I can only get to properties via File, info, properties(in the dropdown box), Advanced properties Once in advanced properties i can click the custom tab but am not able to save anything in that tab.

Any ideas?
Thanks.