+ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print()
+do not print out the time zone: it either prints out "GMT" or nothing. But all
+certificates complying with RFC5280 et al use GMT anyway.
+
+Use the ASN1_TIME_normalize() function to normalize the time value before
+printing to get GMT results.
+
+=head1 RETURN VALUES
+
+ASN1_TIME_set(), ASN1_UTCTIME_set(), ASN1_GENERALIZEDTIME_set(), ASN1_TIME_adj(),
+ASN1_UTCTIME_adj and ASN1_GENERALIZEDTIME_set return a pointer to a time structure
+or NULL if an error occurred.
+
+ASN1_TIME_set_string(), ASN1_UTCTIME_set_string(), ASN1_GENERALIZEDTIME_set_string()
+ASN1_TIME_set_string_X509() return 1 if the time value is successfully set and 0 otherwise.
+
+ASN1_TIME_normalize() returns 1 on success, and 0 on error.
+
+ASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check() return 1
+if the structure is syntactically correct and 0 otherwise.
+
+ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() return 1
+if the time is successfully printed out and 0 if an error occurred (I/O error or
+invalid time format).
+
+ASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if an
+error occurred (invalid time format).
+
+ASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail if the
+passed-in time structure has invalid syntax, for example.
+
+ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if B<s> is
+before B<t>, 0 if B<s> equals B<t>, or 1 if B<s> is after B<t>. -2 is returned
+on error.
+
+ASN1_TIME_compare() returns -1 if B<a> is before B<b>, 0 if B<a> equals B<b>, or 1 if B<a> is after B<b>. -2 is returned on error.
+
+ASN1_TIME_to_generalizedtime() returns a pointer to
+the appropriate time structure on success or NULL if an error occurred.