涵盖了由厚度在0.003 mm和0.35 mm之间的磁性软钢或合金条缠绕而成的环形磁芯的尺寸和结构特征。包括主要尺寸的标准范围，以及带钢厚度、芯子保护、标记和包装的建议。

Covers the dimensional and constructional characteristics for toroidal cores wound from strips of magnetically soft steel or alloy having thickness between 0.003 mm and 0.35 mm. Includes standard ranges of main dimensions and recommendations for strip thickness, core protection, marking and packing.