I don't know how this would be but someone told me tonight that the Kol Yaakov writes that there is a shita that holds a Megillah has to be written c'sidran. I looked through the sefer on Siman 691 but didn't find anything. I made a search on the sefer as well for the word "כסדרן" on Hebrew Books and nothing came up in that Siman. If anyone knows where this is or has any idea who else might bring it down, please share! Thanks!