The Dynamics GP Support blog explains how to Prevent Users from keying incorrect Document Dates in Microsoft Dynamics GP 2010 with DocDateVerify.
Prevent Users from keying incorrect Document Dates in Microsoft Dynamics GP 2010 – Microsoft Dynamics GP Support Blog – Site Home – MSDN Blogs
Microsoft & the GP EcosystemInstall, Upgrade & AdminGP 2010
Archived post from 2012. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.