With project management, once the scope of the project has been defined, it is important to get the approval of stakeholders before proceeding further. If the project is small it might only require a single signature from the main sponsor or client for scope verification however with larger projects there may be a number of stakeholders involved.
With key stakeholders it is crucial to get explicit scope verification which could be a formal signature on paper or via an email that specifically states project approval. Whichever the method, a record of the scope verification should be retained. Of course, the stakeholders should already have been exposed to draft copies of the proposal making the verification process a mere formality.
With other, less involved, stakeholders it is acceptable to get implicit approval or scope verification. In other words the project manager presents the project plan to them for inspection with an ending date for voicing any questions or concerns. After that date if the project management team has not heard from the stakeholder it is assumed that approval has been granted.
With other interested parties the project manager need only deliver to them a copy of the project plan letting them know the document is for informational purposes only. These parties are not in a position to request changes and by this point the project has probably already been approved by the sponsor or main client. The project management team should however be available to answer questions or clarify the parameters of the project.
This term is defined in the 3rd edition of the PMBOK but not in the 4th.