| Description | An index capable of representing an Enhanced Mail System
Status Code. Enhanced Mail System Status Codes are
defined in RFC 1893. These codes have the form
class.subject.detail
Here 'class' is either 2, 4, or 5 and both 'subject' and
'detail' are integers in the range 0..999. Given a status
code the corresponding index value is defined to be
((class * 1000) + subject) * 1000 + detail. Both SMTP
error response codes and X.400 reason and diagnostic codes
can be mapped into these codes, resulting in a namespace
capable of describing most error conditions a mail system
encounters in a generic yet detailed way. |