What is the ruling on drawing a line with a pencil under certain words in the Mushaf to correct mistakes, and is this considered desecration of the Mushaf?

The basic principle is to preserve the Mushaf (definition) (Qur’an) from having anything other than its text written in it. However, it is permissible to place light marks with a pencil in a personal Mushaf, not public ones, to identify the location of a mistake or a point of confusion in memorization. The mark should be erased after it is no longer needed. If erasing would damage the Mushaf's pages, then the old Mushaf should be preserved in a suitable place, and a new Mushaf should be acquired for recitation and review.