zxAnMldGroupForwardingPortList

ZxAnPortList reprensents a map of ports. It uses a complex coding 
to construct a OCTET STRING. 
ZxAnPortList is consisted of many physical port units. Each port 
unit is the type of OCTET STRING which including some bit fields.
             
+-----------+-----------+      +-------------+-------------+ 
| Phy Port 1| Phy Port 2|  ... | Phy Port n-1| Phy Port n  | 
|    Unit   |    Unit   |      |    Unit     |     Unit    | 
+-----------+-----------+------+-------------+-------------+
                              
Each port unit has some bit fields to indicate some information.
The definition of a port unit is as follows.
          
|  Byte 0 |   Byte 1    | Byte 2   |  Byte 3   |Byte 4 .. Byte n|
|---------|-------------|----------|-----------|----------------|
|Unit Size|InterfaceType| Port No. |ServiceType|   Ports List   |
|         |             |(Phy port)|           | (logical port) |
+---------+-------------+----------+-----------+----------------+            
              
Unit Size:      
   The length of this port unit, UNIT is byte.
InterfaceType:  
   The values definition of interfaceType             
       1 - Physical Port
       2 - DSL PVC
       4 - EPON/GPON vport
       5 - ATM PVC
       6 - VDSL PVC
       241 - Smartgroup                               
Port No.:           
    The port No. in a slot.                            
ServiceType:    
    The service is carried by these ports or virtual circuits.  
Ports List:     
    Each octet within this field specifies a set of eight
    ports, with the first octet specifying ports 1 through
    8, the second octet specifying ports 9 through 16, etc.
    Within each octet, the most significant bit represents
    the lowest numbered port, and the least significant bit
    represents the highest numbered port. Thus, each port
    of the service entity is represented by a single bit within 
    the value of this object. If that bit has a value of '1'
    then that port is included in the set of ports, the port
    is not included if its bit has a value of '0'.  
              
For Example:
          
InterfaceType: 1 - Physical Port
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|    1     |    0     |    0     |Physical Ports List   |             
+---------+----------+----------+----------+----------------------+  
          
InterfaceType: 2 - DSL PVC
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|    2     | Port No. |    0     |DSL PVCs List         |             
+---------+----------+----------+----------+----------------------+  
          
InterfaceType: 4 - EPON/GPON vport
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|    4     | Port No. |    ONU   |VPorts List           |             
+---------+----------+----------+----------+----------------------+         
          
InterfaceType: 5 - ATM PVC
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|    5     | Port No. |    0     |ATM PVCs List         |             
+---------+----------+----------+----------+----------------------+                       
          
InterfaceType: 6 - VDSL PVC
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|    6     | Port No. |    0     |VDSL PVCs List        |             
+---------+----------+----------+----------+----------------------+       
          
InterfaceType: 241 - Smartgroup      
|  Byte 0 |  Byte 1  |  Byte 2  |  Byte 3  |Byte 4     ..   Byte n|
|---------|----------|----------|----------|----------------------|
|Unit Size|   241    |     0    |    0     |Smart Groups List     |             
+---------+----------+----------+----------+----------------------+