NFPA®'s Redline PDF contains both the current NFPA document and a Redline version of the document which shows changes from the previous edition marked in color. With the Redline you can quickly spot changed sections and tell specifically what has been changed from the previous edition, saving time and confusion.
Sample (NEC® 2014)
411.2411.3 Definition. Low-Voltage Lighting Systems.
(A) General. Lighting Ssystems Ooperating at 30 Volts- volts or Less. A lighting system consisting less shall consist of an isolating power supply, the low-voltage luminaires, and associated equipment that are all identified for the use. The output circuits of the power supply are shall be rated for not more than 25 amperes and operate at 30 volts (42.4 volts peak) or lessmaximum under all load conditions.
(B) Class 2. Listed Class 2 lighting equipment shall be rated in conformance with Chapter 9, Table 11(A) or Table 11(B).
411.3411.4 Listing Required. Lighting systems operating at 30 volts or less shall comply with 411.3(A)411.4(A) or
411.3(B).411.4(B). Class 2 power sources and lighting equipment connected to Class 2 power sources shall be llisted.