In the 1970s, when resources were severely constricted, the PPs were set up to make optimum use of resources. Over time, as the infrastructure improved, the PPs have been revised. Most PPs are close to the LAC, however in Depsang plains area, the PPs still remain well inside, despite having been revised a number of times. Former Army officers have said that PPs are a better on ground picture of India's limits of control. Based on location, the periodicity of visiting PPs can vary greatly from a few weeks to a couple of months. While some PPs are numbered, others are not, and are identified by geographical landmarks. There are over 65 PPs stretching from Karakoram to Chumar.