So I have an issue with a drawing, all of my contour labels have disappeared in the plan views but are visible in model space. I checked all the layers associated with the labels, made sure they were on, and then did a quick select. The quick select showed that there were labels, so I just started typing commands with "label" in them to see what I could find. A command called "LABELVIEWPORTOVERRULEOFF" showed up and I selected it and all my contour labels reappeared. I now have to complete this command in each of my viewports to get the labels to show. My question is this: where and what is this command? I searched the command on Google and Autodesk, and nothing shows up. How is this command available without any documentation on it, and how did the variable get reset in all of my viewports?

Has anyone ever seen or worked with this command? I would appreciate any information that anyone has on it, so that I can avoid having to deal with this in the future.