Hello, I’ve been asked to provide an OPS-DIR review of draft-ietf-pim-explicit-tracking(-09). In general, I have no problems with the draft, aside from language lawyer issues (listed below) and one minor nit. In general, I find the draft to be well written; there’s a good description of what it wants to cover, decent background that leads you into why the draft covers what it covers, and then of course, the draft content itself. However, Section 4 of the draft required me to re-read it twice. The first four paragraphs are fine; what gives me pause are sentences like “If the router is confident perfectly synchronized …”. While I realize that HOW the router might achieve this confidence is perhaps out of scope, were I trying to implement this, I’d wonder how to achieve this confidence. Further, the fact that this functionality should be disabled by default and the reasons why have a whole section (Section 6) dedicated to them, without further ways to achieve the goals of the draft while mitigating the risks of Section 6 (short of disabling the functionality), I begin to question why I’d want this. And since I read the draft, I’ll point out a few language lawyer things to consider:  - Section 3, Paragraph 3: " In order to simplify the  implementation, Lightweight-IGMPv3/MLDv2 [4] do not keep the state.. ”      Change  “ do not keep the ”  to  “ does not ” - Section 4, Paragraph 4:  “ A router enabling   does not send any specific query message(s) and immediately leave the group or …”   Change “leave the group” to “leaves the group”. I find this sentence a bit wordy and unclear following the “and”.  - Section 7, Paragraph 2: What’s an ordinary router? - Section 10, Paragraph 1: “It gives some impact …”    Change “gives” to “has” Kind regards, Sarah