+=head2 Reporting errors
+
+Each sub-library has a specific macro XXXerr() that is used to report
+errors. Its first argument is a function code B<XXX_F_...>, the second
+argument is a reason code B<XXX_R_...>. Function codes are derived
+from the function names; reason codes consist of textual error
+descriptions. For example, the function ssl3_read_bytes() reports a
+"handshake failure" as follows:
+
+ SSLerr(SSL_F_SSL3_READ_BYTES, SSL_R_SSL_HANDSHAKE_FAILURE);
+
+Function and reason codes should consist of upper case characters,
+numbers and underscores only. The error file generation script translates
+function codes into function names by looking in the header files
+for an appropriate function name, if none is found it just uses
+the capitalized form such as "SSL3_READ_BYTES" in the above example.
+
+The trailing section of a reason code (after the "_R_") is translated
+into lower case and underscores changed to spaces.
+
+Although a library will normally report errors using its own specific
+XXXerr macro, another library's macro can be used. This is normally
+only done when a library wants to include ASN1 code which must use
+the ASN1err() macro.
+
+