When The F2 lookup option is set to not to "Allow blank input" on a field but the field isn't populated and GMPE doesn't warn you. However If you touch the record in GMWeb it doesn't let you leave the contact unless that field is populated.
Do to the differences between a web application, and a desktop client application there will be some differences in behavior based on the F2 lookup settings used. In this case the GoldMine Web product reviews the field requirements when the record is opened. So it must apply the settings immediately, thus preventing the record from being closed until the requirement is met.
In GoldMine Premium the field requirements are not evaluated unless the user tabs or clicks into the field. As such the user can open the record, and close the record without making any changes.
Even though the behavior is slightly different in the two products, the behavior each product does have is correct for that product.
Related to RM 235547.