Also called the Lower Three Emperors by some, this is a set of three separate points that are frequently used together. You'll notice they are on the Spleen channel, so they treat the Earth element (Spleen/Stomach), yet Shen Guan (77.18) has a strong effect on the Water element (Kidney) as well.
Shen Guan (77.18) Use you fingernail to find this point! As Dr. Robert Chu says, "use your nail, you cannot fail!" Shen Guan is located 1.5 cun distal to Spleen 9 and right along the edge of the bone. That's a little different than you learn in school. This is because this point has a strong effect on the Kidney and bone is the tissue associated with Kidney.
Di Huang (77.19) Di Huang is 4 cun proximal to Spleen 6. Dr. Wei Chieh Young says you actually locate this point by locating Shen Guan and Ren Huang (the next point), then palpate the channel at approximately the mid point between these two. But that' s not all. You also palpate the Liver and Kidney channels in this area to find the "soft" or "hollow" spot here. That is the real location of Di Huang. But until you get comfortable with this, 4 cun proximal to Spleen 6 will do.
Ren Huang (77.21) This point is located 3 cun proximal to the apex (highest point) of the medial malleolus. This point will probably overlap with Spleen 6.