As has been mentioned in this thread already, column text can have a number of functions.
I thought I would include an example from a 14th-century manuscript where the column text was specifically written as instructions to an illustrator to add embellished initials. For some reason, the drawings were done, but the initials were never finished. Perhaps a different person was assigned to this task or perhaps something interrupted the process.
It's interesting that they didn't always remove the small initials when adding the embellished version. I've seen quite a few manuscripts where you can see the instruction under the finished initial.
I thought I would include an example from a 14th-century manuscript where the column text was specifically written as instructions to an illustrator to add embellished initials. For some reason, the drawings were done, but the initials were never finished. Perhaps a different person was assigned to this task or perhaps something interrupted the process.
It's interesting that they didn't always remove the small initials when adding the embellished version. I've seen quite a few manuscripts where you can see the instruction under the finished initial.

