1. A method comprising: generating a first customized document including conditional and non-conditional content; generating a second customized document including conditional and non-conditional content; and generating an amended second customized document incorporating amendments made to the first customized document resulting in an amended first customized document, including the steps of: determining which portions of document content are comprised in the amended first customized document but which are not comprised in the second customized document; deleting the portions of document content determined in the preceding step from the amended first customized document; determining which portions of document content are comprised in the second customized document but which are not comprised in the amended first customized document; copying the portions of document content determined in the preceding step from the second customized document to the amended first customized document; and outputting the resulting amended first customized document as the amended second customized document.