At the 20th CGPM (1995), it was recognised that although ad-hoc recognition of instrument calibration between cooperating countries had been taking place for a hundred years, a need had arisen for a more comprehensive agreement.
在1995年的第二十届国际计量大会（CGPM）上，大家意识到虽然合作的国家之间特定的仪器校准已有一百多年的历史，但已经迫切需要一个更全面的协议。