Original sentence: (Canada uses a P-series of sizes, which are the American paper sizes rounded to metric dimensions).Prior to the adoption of ISO 216, many different paper formats were used internationally.The lengths of JIS B series paper are approximately 1.22 times those of A-series paper.The principal countries not generally using the ISO paper sizes are the United States of America and Canada, which use the Letter, Legal, and Executive system.There is also an incompatible Japanese B series defined by the JIS
Edited sentence: (Canada uses a P-series of sizes, which are nothing more than the American paper sizes rounded to metric dimensions).(There is also an incompatible Japanese B series, defined on the basis of the arithmetic mean instead of the geometric mean.Prior to the adoption of ISO 216 worldwide, many different paper formats were used internationally.The main holdbacks in this area are the United States of America and Canada, which continue to use the Letter, Legal, and Executive system