I haven't seen the Shaolin Internal Skill Classic, but if it's twelve moves, it can be determined that it's the Dharma Yijin Sutra or the Twelve Great Techniques. The Dharma Yijin Sutra is a simplified version of Yijin Sutra and the internal strength diagram of pulp washing, and it is better to improve internal force in 12 kungfu. Twelve-type meditation, in the theory of strengthening tendons and washing marrow, belongs to the mode of washing marrow. But I don't know the specific source, and I know little about the pulp washing sutra. The Buddhist Yijin Sutra, the 12th National Congress of the Communist Party of China, has achieved good results. You can find relevant videos on the Internet to determine whether they are consistent. To be clear, the difficulty of Yijinjing lies in the correct study, and then it is not difficult to stick to Yijinjing itself.
* * * The best way to identify the effect is to add the internal strength diagram of relaxing tendons and washing pulp, but the movements are the most and the most difficult. Then there are the Buddhist Yijinjing, the Twelve Merits, the Yijinjing of Xiongshi and the essence of Shaolin Boxing.