I sent this very same question to my local carrier, FCSO and this was the response.
1. If I document the most pertinent systems under the ROS, review the rest of the systems but document remaining 13-point review of system was unremarkable or non-contributory, will I receive credit for a complete ROS.?
1. If the remaining systems were, indeed, reviewed and were found to be unremarkable, yes. Avoid the use of 'noncontributory', as it implies the system was never inquired about.
I do not allow non-contributory, however I will allow unremarkable.