I was going to implement "IF MOFFICE <> 'SN' OR MOFFICE <> 'VS'" but I had to resort to "IF MOFFICE <> 'SN' AND MOFFICE <> 'VS'". The idea is to only allow entry of SN or VS, thus my reason for attempting to use OR instead of AND.
"Build a man a fire, and he's warm for a day.
Set a man on fire, and he's warm for the rest of his life."