using L<X509_verify_cert(3)> or L<X509_STORE_CTX_verify(3)> has indicated
an error or in a verification callback to determine the nature of an error.
-X509_STORE_CTX_get_error() returns the error code of B<ctx>, see
-the B<ERROR CODES> section for a full description of all error codes.
+X509_STORE_CTX_get_error() returns the error code of I<ctx>.
+See the L</ERROR CODES> section for a full description of all error codes.
+It may return a code != X509_V_OK even if X509_verify_cert() did not indicate
+an error, likely because a verification callback function has waived the error.
X509_STORE_CTX_set_error() sets the error code of I<ctx> to I<s>. For example
it might be used in a verification callback to set an error based on additional
failure and internal errors) they can also return a negative code.
On error or failure additional error information can be obtained by
-examining I<ctx> using, for example, L<X509_STORE_CTX_get_error(3)>.
+examining I<ctx> using, for example, L<X509_STORE_CTX_get_error(3)>. Even if
+verification indicated success, the stored error code may be different from
+X509_V_OK, likely because a verification callback function has waived the error.
=head1 SEE ALSO