According to Brant Gardner, Jarom makes a brief but important note at the end of Omni 1:14. He notes that the other plates (the large plates) are "according to the writings of the kings, or those which they caused to be written." This is important because it is apparently a significant shift from the time of Nephi, who kept the records himself as the king. It is likely that his next successor (or two) also kept them personally, but by the time of Jarom the political and social complexity seems to be sufficient that the kings cause them to be written. This is a subtle but unmistakable indication of the increasing complexity and stratification of Nephite society (which, as we remember, was a theme against which Jacob had preached--see Jacob 2). [Brant Gardner, "Book of Mormon Commentary," [http://www.highfiber.com/~nahualli/] LDStopics/Jarom/Jarom1.htm, p. 15]
Jarom 1:14-15 I [Jarom] deliver these [small] plates into the hands of my son Omni (Nephite Record Keepers) [[Illustration]]: Nephite Record Keepers. Adapted from [Church Educational System, Book of Mormon Student Manual: Religion 121 and 122, 1989, p. 155]