NNR CONDITION,ITRF AND GLOBAL PLATE MOTION MODEL
NNR条件，ITRF和全球板块运动模型

Through the analysis of the difference between two plate motion models computed from ITRF2000,it is concluded that ITRF2000 is aligned with NNR-NUVEL1A at 1 mm/a level,i.e.,it satisfies NNR condition;it is not enough to judge whether ITRF satisfies NNR condition just according to if the sum of global angular momentum is zero or not.