module HCNUM-TC {

      yang-version 1;

      namespace
         "urn:ietf:params:xml:ns:yang:smiv2:HCNUM-TC";

      prefix "hcnum-tc";

      import yang-smi {
         prefix "smi";
      }
      import ietf-yang-types {
         prefix "yang";
      }

      organization "IETF OPS Area";

      contact
         "        E-mail: mibs@ops.ietf.org
         Subscribe: majordomo@psg.com
           with msg body: subscribe mibs
         
         Andy Bierman
         Cisco Systems Inc.
         170 West Tasman Drive
         San Jose, CA 95134 USA
         +1 408-527-3711
         abierman@cisco.com
         
         Keith McCloghrie
         Cisco Systems Inc.
         170 West Tasman Drive
         San Jose, CA 95134 USA
         +1 408-526-5260
         kzm@cisco.com
         
         Randy Presuhn
         BMC Software, Inc.
         Office 1-3141
         2141 North First Street
         San Jose,  California 95131 USA
         +1 408 546-1006
         rpresuhn@bmc.com";

      description
         "A MIB module containing textual conventions
         for high capacity data types. This module
         addresses an immediate need for data types not directly
         supported in the SMIv2. This short-term solution
         is meant to be deprecated as a long-term solution
         is deployed.";

      revision "2000-06-08" {
         description
            "Initial Version of the High Capacity Numbers
            MIB module, published as RFC 2856.";
      }


      typedef CounterBasedGauge64 {
         type yang:counter64;
         description
            "The CounterBasedGauge64 type represents a non-negative
            integer, which may increase or decrease, but shall never
            exceed a maximum value, nor fall below a minimum value. The
            maximum value can not be greater than 2^64-1
            (18446744073709551615 decimal), and the minimum value can
            
            not be smaller than 0.  The value of a CounterBasedGauge64
            has its maximum value whenever the information being modeled
            is greater than or equal to its maximum value, and has its
            minimum value whenever the information being modeled is
            smaller than or equal to its minimum value.  If the
            information being modeled subsequently decreases below
            (increases above) the maximum (minimum) value, the
            CounterBasedGauge64 also decreases (increases).
            
            Note that this TC is not strictly supported in SMIv2,
            because the 'always increasing' and 'counter wrap' semantics
            associated with the Counter64 base type are not preserved.
            It is possible that management applications which rely
            solely upon the (Counter64) ASN.1 tag to determine object
            semantics will mistakenly operate upon objects of this type
            as they would for Counter64 objects.
            
            This textual convention represents a limited and short-term
            solution, and may be deprecated as a long term solution is
            defined and deployed to replace it.";
      }

      typedef ZeroBasedCounter64 {
         type yang:counter64;
         description
            "This TC describes an object which counts events with the
            following semantics: objects of this type will be set to
            zero(0) on creation and will thereafter count appropriate
            events, wrapping back to zero(0) when the value 2^64 is
            reached.
            
            Provided that an application discovers the new object within
            the minimum time to wrap it can use the initial value as a
            delta since it last polled the table of which this object is
            part.  It is important for a management station to be aware
            of this minimum time and the actual time between polls, and
            to discard data if the actual time is too long or there is
            no defined minimum time.
            
            Typically this TC is used in tables where the INDEX space is
            constantly changing and/or the TimeFilter mechanism is in
            use.
            
            Note that this textual convention does not retain all the
            semantics of the Counter64 base type. Specifically, a
            Counter64 has an arbitrary initial value, but objects
            defined with this TC are required to start at the value
            
            zero.  This behavior is not likely to have any adverse
            effects on management applications which are expecting
            Counter64 semantics.
            
            This textual convention represents a limited and short-term
            solution, and may be deprecated as a long term solution is
            defined and deployed to replace it.";
      }
   }  // module HCNUM-TC