Under-delivery and over-delivery of ad impressions, plus campaign flighting (failing to give an even distribution of ads through the campaign period), will be tackled in the new guidance, set to be published by early 2007.
Clients and online media owners will be consulted via trade bodies the Incorporated Society of British Advertisers, the Internet Advertising Bureau and the Association of Online Publishers.
"Ensuring our clients' campaigns are delivered as purchased is the number one basic requirement for our industry," said Wayne Arnold, chairman of IPA Digital and managing director of Profero.
Despite being mooted for some time, the trigger for drafting new rules was the decision by online media owners to impose late copy surcharges on advertisers from April 1.
"We endorse that principle," said IPA media business manager Nigel Gwilliam.
"But media owners also have to deliver campaigns fairly and accurately."
With the online ad industry expected to touch £2bn by the end of 2006, "it is now that it is really maturing and that we need to introduce clear and concrete guidelines", Gwilliam added.
Historically, the level of variance for campaign delivery has been informally accepted as 10 per cent under or over.
This article was first published on Direct Response