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Colleagues, Comment I-4, which I have submitted, asks to delete a sentence in 99.1 which is to be added by this amendment. The comment text is "The clause is applicable to full-duplex operation with 10BASE-T1L (Clause 146) and
10BASE-T1S (Clause 147) PHYs and all PHYs 100 Mb/s and above (See Figure 1-1)" This sentence was added in D2.1 as a result of comment #39 against D2.0, and that
comment also inserted some text related to half-duplex operation. The text related to half-duplex was subsequently removed, as a results of multiple
comments against D2.1; so now clause 99 is applicable only to full-duplex operation, as
stated in the first sentence, preceding the quoted sentence. The quoted sentence thus
became redundant. Additionally, the quoted sentence breaks the flow of its preceding sentence, which
mentions "a pair of full-duplex MACs", and its subsequent sentence, which starts with "The
two MACs are". The only remaining effect of the quoted sentence is noting that full-duplex operation is also
possible in 10BASE-T1L and 10BASE-T1S. But this information is out of place in this
clause. The proposed response to this comment states: “While the commenter is correct that the extra sentence was added to provide clarity in
a broader context, it still provides additional clarity to the use of Clause 99,
especially since the 10BASE-T1S PHY has a half-duplex shared-medium mode of operation.” The last phrase (highlighted) raises another aspect of the problem: the text also addresses “and all PHYs 100 Mb/s and above”,
and there are several PHYs in that group that also have half-duplex shared-medium mode of operation. Only 10BASE-T1S and 10BASE-T1L are currently pointed out, so are the others excluded of this statement (such that the clause is applicable in their half-duplex
mode too)? If we follow the logic of the response, the text should be changed from "The clause is applicable to full-duplex operation with 10BASE-T1L (Clause 146) and
10BASE-T1S (Clause 147) PHYs and all PHYs 100 Mb/s and above (See Figure 1-1)" to "The clause is applicable to full-duplex operation with 10BASE-T1L (Clause 146), 10BASE-T1S (Clause 147),
and all PHYs 100 Mb/s and above (See Figure 1-1)” Or alternatively list all the 100 Mb/s and above that have a half-duplex option, such that there is no distinction. Either way, I still think the sentence would be redundant, because the preceding statement “This clause specifies an optional MAC Merge sublayer operating in a station with a pair of full-duplex MACs” makes things crystal
clear. Please note that while this amendment focuses on “changes to IEEE Std 802.3-202x to add 10 Mb/s Single-Pair Ethernet point-to-point PHYs to the PHYs supporting the MAC Merge function and the
Time Synchronization Service Interface (TSSI)”, when it is eventually integrated into the full standard, mentioning these PHYs explicitly and exclusively in other areas of the standard (such as clause 99) would seem weird. That is
what I’m pointing to at the end of the comment. If it is desired to emphasize that MAC merge is not applicable to half-duplex operation (even though it’s already stated that it applies to full-duplex), this could be done more cleanly by an addition of a separate sentence
after the first dashed list, such that the clause starts as follows: This clause specifies an optional MAC Merge sublayer for use with a pair of full-duplex MACs and a single
PHY operating at 100 Mb/s or higher on a point-to-point link. The two MACs are: — a preemptable MAC (pMAC), which carries the preemptable traffic, and — an express MAC (eMAC), which carries the express traffic. This clause is not applicable to half-duplex operation.
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