ArcMap layout view - What does the drop shadow on the page mean?

[AfsiMoaveni]

I recall reading that the drop shadow in the ArcMap layout view had some significance (whether some parameter was set or not), but I cannot recall the meaning. Image shows the area I am asking about.

[DanPatterson_Retired]

I am not sure what you mean about significance, except for aesthetics or personal preference... to provide the sense of depth to an output

http://desktop.arcgis.com/en/arcmap/latest/map/page-layouts/customizing-data-frames.htm

it is an element of the frame

http://desktop.arcgis.com/en/arcmap/latest/map/page-layouts/map-elements.htm

[XanderBakker]

I'm note sure it this really has effect on exported or printed results (I haven't tried though).Since the drop shadow shows its effect outside the page, I don't think it is considered in the export or print. You can change the drop shadow settings of your map frame/data frame and when the frame does not occupy the entire page, you will see that in the exported and printed results.

In this old blog Figure-ground: Drop shadow | ArcGIS Blog  they mention drop shadows used for geographic features (which is different).

There is a thing with transparencies that would rasterize all the layer below it.

[AfsiMoaveni]

Thank you, but I am not talking about drop shadows that I would add as a user for aesthetic purposes. I am referring to the the overall layout page's drop shadow that ArcGIS adds.  I just figured it out myself (somehow posting makes me realize the answer, this has happened before :-)). It's the Print setting. See attached. If it's selected to Use printer paper setting, you get the drop shadow. If unclicked, no shadow.