1. For each reduction of 0.01% below the specified maximum carbon content, an increase of0.05% above the specified maximum manganese content is permissible, up to a maximumof 1.5% for grades X42 through X52, up to a maximum of 1.65% for grades higher than X52but less than X70, and up to 2.00% for grades X70 and higher.
2. Columbium (niobium), vanadium, titanium, or combinations thereof may be used byagreement between purchaser and manufacturer.
3. Columbium (niobium), vanadium, titanium, or combinations thereof may be used at thediscretion of the manufacturer.
4. The sum of columbium (niobium), vanadium and titanium contents shall not exceed 0.15%.
5. Other chemical compositions may be furnished by agreement between the purchaser andmanufacturer, providing that the limits of note 4 and the tabular limits of Phosphorous & Sulphur are met.