Technique number 1 is the most rigorous technique because the bench mark heights will retain their original relative accuracy.  These heights will be useful to all users. In addition, NGS will adjust and publish the results if the data are submitted to NGS in computer-readable form. Technique number 2 may meet many users’ requirements, but depending upon the accuracy requirements and the complexity of the users’s leveling network, may prove to NGS to process.  Technique number 3 should be the easiest method to implement, but in general is only sufficiently accurate enough to meet mapping requirements.