tmnxTestHdSapEncapValue

The value of the label used to identify the entity using the specified
encapsulation value on a specific port.
          
The format of this object depends on the encapsulation type defined on
this port.
          
When the encapsulation is nullEncap the value of this object must be
zero.
          
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 00000000 00000000|
+--------+--------+--------+--------+
          
When the encapsulation is dot1qEncap the value of this object is equal
to the 12-bit IEEE 802.1Q VLAN ID.
          
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
Bit 31 is set to 0 in the case of tagged-VLAN.
Bit 31 is set to 1 in the case of dotq-CP as follows:
31                                   0
+--------+--------+--------+--------+
|10000000 00000000 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is mplsEncap the value of this object is equal
to the 20-bit LSP ID.
          
31                                   0
+--------+--------+--------+--------+
|00000000 0000XXXX XXXXXXXX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is qinqEncap, the value of the outer 802.1Q
VLAN ID is encoded in the least significant 16 bits, and the value of
the inner VLAN ID is encoded in the most significant 16 bits.
          
31   inner             outer       0
+--------+--------+--------+--------+
|0000YYYY YYYYYYYY 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
where:
    - '*' is represented as 4095.
    - '0' is represented as 0.
    - any other value in between as a valid tag.
    - '*.null' is represented in the following way:
          
      31                                  0
      +--------+--------+--------+--------+
      |10000000 00000000 00001111 11111111|
      +--------+--------+--------+--------+
          
    - 'null.null' is represented in the following way:
          
      31                                  0
      +--------+--------+--------+--------+
      |10000000 00000000 00010000 00000000|
      +--------+--------+--------+--------+
          
Bit 30 is set to 0 in the case of tagged-qinq for the inner tag. Bit
30 is set to 1 in the case of qinq-CP with inner tag. Bit 15 is set to
0 in the case of tagged-qinq for the outer tag. Bit 15 is set to 1 in
the case of qinq-CP with outer tag.
          
Example of qinq encoding for CP.* saps:
          
31                                   0
+--------+--------+--------+--------+
|00001111 11111111 100XXXXX XXXXXXXX|
+--------+--------+--------+--------+
          
          
Example of qinq encoding for qtag.CP saps:
          
31                                   0
+--------+--------+--------+--------+
|010XXXXX XXXXXXXX 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
Some ports have a restrictions to the encapsulation types that they
can support and hence impose restrictions on the respective formats
defined above.