Avoid PHP undefined index warning, if a second pipe isn't used in the extrafield definitions.
Avoid PHP warnings if the selected View doesn't set the 'exclude' field property.
When viewing nodes with a nodereference_views_multifield, continue to display selected nodes which were but are no longer part of the nodereference_views_multifield's view. In other words, if a lineitem was ordered, but is then no longer offered for sale (no longer present in products view), still display it as part of the order.
When updating to this release (nodereference_views_multifield-6.x-1.5), you will need to configure the newly added permissions — otherwise no users except UID 1 will be able to select rows or edit extrafields.
Set both #value and #attributes on checkboxes, in case the form is submitted without being sent to the browser (via an internal node_form_submit() call, via comment_driven.module for example)
