API Specification 10A specifies requirements and gives recommendations for eight classes of well cements, including their chemical and physical requirements and procedures for physical testing. This specification is applicable to well cement Classes A, B, C, D, E and F, which are the products obtained by grinding Portland cement clinker and, if needed, calcium sulfate as an interground additive. Processing additives may be used in the manufacture of cement of these classes. Suitable set-modifying agents may be interground or blended during manufacture of Classes D, E and F. API Spec 10A is also applicable to well cement Classes G and H, which are the products obtained by grinding Portland cement clinker with no additives other than calcium sulfate or water. This edition of API Spec 10A is an adoption of ISO 10426-1:2000 with editorial changes and the addition of an API Monogram Annex.