r the curve encoding uses explicit parameters or a named curve using an ASN1 OID: many applications only support the latter form. If asn1_flag is <b>OPENSSL_EC_NAMED_CURVE</b> then the named curve form is used and the parameters must have a corresponding named curve NID set. If asn1_flags is <b>OPENSSL_EC_EXPLICIT_CURVE</b> the parameters are explicitly encoded. The functions EC_GROUP_get_asn1_flag() and EC_GROUP_set_asn1_flag() get and set the status of the asn1_flag for the curve. Note: <b>OPENSSL_EC_EXPL