版权许可中的circulation是什么意思

circulation 英[?s?:kj??le??n] 美[?s?:rkj??le??n] n. 血液循环; 流通，传播; 发行量; 社交活动（某段时间的）; [例句]It says the third-party companies were sponsors of a circulation initiative at the paper.它说那些第三方公司是该报发行活动的赞助商。