MB3 190b: Laws of Writing on Shabbos (340:4 - part 3)

Writing with the back of one's hand on Shabbos, with one's non-dominant hand, or writing backwards.

An amputee whose normal way of writing is with his/her foot, etc.

An adult holding the hand of a child holding a pen.

רושם: Painting designs on a wall, taking a photo with film, and x-rays on Shabbos, walking past security cameras on Shabbos. Recording audio or video on Shabbos.

Tearing a piece of paper between the letters

Erasing two letters to write one large letter, erasing with one's left hand.