ASN1_TIME_to_tm() converts the time B<s> to the standard B<tm> structure.
If B<s> is NULL, then the current time is converted. The output time is GMT.
-Only the B<tm_sec>, B<tm_min>, B<tm_hour>, B<tm_mday>, B<tm_mon> and B<tm_year>
-fields are updated.
+The B<tm_sec>, B<tm_min>, B<tm_hour>, B<tm_mday>, B<tm_mon> and B<tm_year>
+fields of B<tm> structure are set to proper values, whereas all other fields
+are set to 0. If B<tm> is NULL this function performs a format check on B<s>
+only.
ASN1_TIME_diff() sets B<*pday> and B<*psec> to the time difference between
B<from> and B<to>. If B<to> represents a time later than B<from> then