1. Tsis tu ncua xyuas seb puas muaj cov khib nyiab thaiv qhov chaw ntawm lub hnab lim thiab yog tias cov khoom lim dej puas lawm;
2. Yog tias cov khoom thaiv qhov chaw, nws yuav tsum tau muab tshem tawm;
3. Yog tias qhov chaw ntawm cov khoom siv lim tau raug mob hnyav, nws yuav tsum tau hloov nrog cov khoom lim tshiab los yog hloov nrog cov lim tshiab rau kev txhim kho;
4. Thaum txhim kho lub lim, xyuas kom meej tias lub siab ntawm cov ncej yog kaw zoo kom tsis txhob muaj cua nkag;
5. Tsis txhob tsoo lub lim dej nrog cov khoom hnyav, thiab tsis txhob rub lub lim dej quab yuam;
6. Thaum txhim kho lub tshuab lim dej nruab nrab, qhov ntev ntawm lub hnab lim lub qhov ncauj yuav tsum yog perpendicular mus rau hauv av kom ntseeg tau tias cov khoom siv cua lim tau zoo thiab ua rau lub neej ntev.