What do these yellow markings on the leave tips mean?

Let me start by saying that i have personal experience with this over my first several grows. The burning tips sometimes called "greenhouse tips" (or so ive been told) are the first indication of nutrient burn (overfeeding) or a pH problem. It starts at the tips of the leaves and works it's way up the leaf. 2 questions. Do you test the ppm of your runoff? And do you test the pH? Of you do then you are already in a great position to stop this. Depending on your grow medium, soil or hydro, you will need to make sure you pH is at a certain level. 6.2-6.8 in soil. (I'm a soil grower) I believe it is lower for hydro but I'm not certain. And your ppm you want around 1000ppm in flower. The burnt tips will never go away but you can stop the spread. They are the first sign like I said. I've seen them in every grow I've done except the last 2 because I started to test pH and ppm. Found out I was way overfeeding my plants. Doing great now though