For legs and hips of the same color use entry 970c00.
For differently colored legs and hips use entries 970xABC where ABC is 3-digit LEGO Color ID of the hips.
For example, 970x026 - Legs and Black Hips.
Note the difference with Bricklink catalog where hips and legs are indexed by the color of the legs, e.g. 970c11 - 'Hips and Black Legs'.
Click on a colored part below to see the Sets and MOCs that use part 970x023 Legs and Blue Hips in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.