NID_crl_reason
if (X509_REVOKED_add1_ext_i2d(rev, NID_crl_reason, rtmp, 0, 0) <= 0)
res = add1_extension(pexts, NID_crl_reason, 0 /* non-critical */, val);
{"CRLReason", "X509v3 CRL Reason Code", NID_crl_reason, 3, &so[755]},
NID_crl_reason, 0, ASN1_ITEM_ref(ASN1_ENUMERATED),
reason = X509_REVOKED_get_ext_d2i(rev, NID_crl_reason, &j, NULL);