What are the solar terms of the Cold Food Festival? What's the point?

The Cold Food Festival, also known as "No-smoking Festival", "Cold Food Festival" and "Hundred Five Days Festival", is one hundred and five days after the summer calendar and one or two days before Tomb-Sweeping Day. When the first day of the day is a holiday, smoking is forbidden and only cold food is eaten. In the development of later generations, the customs of sweeping, hiking, swinging, cuju, pulling hooks and breaking eggs were gradually increased. The Cold Food Festival lasted for more than 2,000 years and was once called the largest folk festival. Jie Zitui, a famous minister and righteous man in the State of Jin in the Spring and Autumn Period. Legend has it that during Jin Wengong's exile, meson tui once cut shares to satisfy his hunger. After Jin Wengong returned to China and proclaimed himself emperor, he forgot to push when he was enfeoffed. Jiezitui didn't want to boast about his achievements and compete for favor, so he took his mother to live in seclusion in Mianshan. Later, Jin Wengong personally went to Mianshan to find Jiezitui, who didn't want to be an official and hid in the mountains. Wen Gong's people released Yamakaji. The intention is to force mesons to show their faces. As a result, meson pushed his mother and was burned to death under a big tree. In order to commemorate this loyal minister's righteous act, he didn't make a fire to cook on the day of Jiezitui's death, but wanted to eat cold food. This is the so-called Cold Food Festival.