User:DMacks/Cyclopropane

Hovering over the upper-left image, which is a file from commons, displays the ImageName field in the popup. Hovering over the upper-right image, which is a file from commons, does not give a popup (there is no ImageName field for it). Hovering over the lower-left image, which is local file, displays the file-description page in the popup. Inconsistent popup behavior makes it hard to set a legend or link to a page describing how to read these different standard diagram styles.