1. A computer-implemented method comprising: obtaining an electronic document in a first format, the electronic document comprising a graphic object represented using a main dataset and a private dataset; normalizing the main dataset of the graphic object of the electronic document stored in an object model in memory; computing a checksum for the normalized main dataset of the graphic object; comparing the computed checksum with a stored checksum located in the private dataset of the electronic document; and converting the electronic document from the first format to a second format based in part on a result of the comparing, wherein the converting comprises, when the computed checksum and the stored checksum do not match, propagating a change from the main dataset to the private dataset.
2. The method of claim 1 , wherein the computed checksum and the stored checksum comprise hash codes, the computing comprises computing multiple hash codes for the normalized main dataset, each computed hash code corresponding to one of the graphic object or an attribute of the graphic object, and the comparing comprises comparing the computed hash codes with stored hash codes located in the private dataset.