<h1>Standard input-output norms limit permissible imported inputs for carbon steel forgings and require proof of use in exports.</h1> Standard input-output norms under SION C359 set permissible imported inputs for machined carbon and alloy steel forgings above 100 kg per piece: specified forging-quality feedstock measured as input content per unit of export; rust-preventing chemicals limited as a proportion of FOB value; and miscellaneous consumables and tooling limited under a separate FOB proportion. Applicants must ensure imported goods match the listed inputs and are actually used or required in the manufacture of the exported forgings, with authorities determining permissible input proportions for resultant products.