1. A method of updating an old version of content on a storage device, comprising: (i) obtaining a compact update package, said compact update package includes: a conversion element, a modified delta, and an indication of forward update or backward update, wherein the conversion element comprises numeral or reference shift rules reflecting differences between the old version of content and a new version of content, wherein the modified delta is a delta between one of: (1) the old version of content and a modified version and (2) a modified version and the new version of content, and wherein the modified version used to produce the modified delta in the compact update package was generated by applying the conversion element to (1) the new version of content in the case of the modified delta being a delta between the old version of content and the modified version, and (2) the old version of content in the case of the modified delta being a delta between the modified version and the new version of content; (ii) determining whether the indication in the obtained compact update package is forward update indication or backward update indication; (iii) in the case of forward update indication: a. generating a modified version to be used to generate a new version of content in step (iii)(b) by applying the conversion element to the old version of content on the storage device; and b. generating the new version of content on the storage device by applying the modified delta to the modified version generated in (iii) (a), wherein the modified delta is a delta between the modified version and the new version of content each used to produce the modified delta of the compact update package; (iv) in the case of backward update indication: a. generating a modified version to be used in step (iv)(b) to generate a new version of content by applying the modified delta to the old version of content on the storage device, wherein the modified delta is a delta between the old version of content and the modified version each used to produce the modified delta of the compact update package; and b. generating the new version of content on the storage device by applying said conversion element to the modified version generated in (iv) (a).