The Encyclopedia has seen several editions (the 3rd edition being a common benchmark). If you do find a digital version, ensure it is the most recent one. Diving science—particularly our understanding of decompression and dive computer algorithms—evolves over time. How to Use the Encyclopedia for Professional Training
The fundamental physics and physiology of diving have not changed. Boyle's Law works the same today as it did in 1985. However, equipment and dive computers have evolved radically. padi encyclopedia of recreational diving pdf