which reviewed many of the legal issues raised by paper-based legal rules : the requirement for a “ written document ” , “ signature ” or “ original ” , the evidential value of electronic messages , the storage of electronic messages , documents of title and negotiability , allocation of liability , validity and formation of contracts , and incorporation by reference . Many of these issues had been raised in prior studies by the United Nations Economic Commission for Europe ( ECE ) '' Legal aspects of trade data interchange : Review of definitions of ‘ writing ’ , ‘ signature ’ , and ‘ document ’ employed in multilateral conventions and agreements relating to international trade ” , TRADE/WP.4/R.1096 , 1994 .