Cov yam ntxwv ntawm cov kabmob ntawm cov kabmob

1. Cov kabmob ua ke nrog cov kabmob tseem ceeb thiab lub rooj zaum bearing. Lub sab nraud ntawm cov kabmob feem ntau yog cov kabmob sab nraud ntawm sab nraud, ua ke nrog lub rooj zaum bearing nrog lub puab qhov ntawm lub puab kheej kheej;

2. Muaj ntau hom qauv, zoo generality thiab interchangeability;

3. Muaj kev hloov kho lub plawv zoo thiab kev sib khi, uas tuaj yeem ua haujlwm hnyav;

4. Yooj yim rau siv thiab yooj yim rau nruab.