preventing changes once WF underway

[John A Haworth]

HI all
 
Could anyone offer advice on the following:
 
I have a sales document that, once created has to go though a number of
review panels, how can I prevent further changes being made to the sales
document, whilst it is going through the various reviews, e.g. for
consistency, I dont want item quantities being inadvertently changed whilst
the doc is between the various reviews (by non-workflow agents), the
workflow agents themselves could make changes.
 
Thanks in advance
 
John