The multicol CR includes example XVII:

If a tall image is moved to a column on the next page to find room for it, its natural column may be left empty. If so, the column is is still considered to have content for the purpose of deciding if the column rule should be drawn.

This is in the current ED as Example 20.

In July 2013 this comment was made,

Second, I am not entirely sure what is meant by "natural column" in Example XVII; it seems to be the column box of first row, with the second row being on next page. For sure, I would want to see a real example with code here.
"next page to find room for it" suggests that such example can only happen in paged media.

The suggestion was to remove the example, I've been unable to find a resolution or further detail on this and the example is still in the spec. Anyone with thoughts, please comment.