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[HSSG] Trowbridge_01_0907.pdf comment about 49.2.4.3



I want to respond to the comment made on page 7 of the
trowbridge_01_0907 presentation that says the text about unused type
field values is too weak. 

Steve felt that the language in 49.2.4.3 was too weak to ensure that
unused values of the type field aren't used - that subclause doesn't
have a shall statement about transmission and receipt of reserved
values. The reason a statement doesn't appear there is that the behavior
is controlled by the state machines and we didn't want to double specify
it.

Look at the R_BLOCK_TYPE and T_BLOCK_TYPE functions defined in
49.2.13.2.3. Any block type that doesn't meet the defined types gets the
value E which causes the transmit and receive state machine to turn it
into the error block.

Use of reserved type field values is fully covered - It is just done in
a different location in the Clause.

Pat