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General Comment: In INTRODUCION, showing the muon geometrical acceptance for one of key physics channels (e.g., h → 4 μ)would be logical to motivate the muon upgrade in 1.6 < |Eta| < 2.2. Then, followed by sections for technology, performance (trigger and reconstruction), construction (electronics, DAQ and integration).

[*] Page 5 (Sec 2.1)

General Comments: "Gain uniformity better than15%".(Line 261) .. We need to translate this as quality control of "hole" size (better than 5%) on each GEM foil.

(a) at the end of Sec 2.1, the text is missing in the last sentence; (b) Fig.2.2 … Change to “Collection” to “Induction” to be consistent Fog. 2.8 and 2.25.

[*] Page 11 (Sec 2.2)

This could be minor (and time consuming if we want to modify the figure). But in Fig. 2.8, GEM1, GEM2, GEM3 are defined in an opposite order (See Fig.2.2 and 2.25).

[*] Page 12 (Sec 2.2) ... comments on text for clarity in reading.

[*] Page 13 (Se 2.2)

[*] Page 17 (Fig. 2.16 in Sec .2.2)
Fig. 2,16 show the cluster size distribution. We have been using the different distribution in the simulation. See the attached slide shown at GEM workshop in March 2014.

* p17_Fig2.16.pdf: Page 17 (Fig. 2.16)

[*] Page 18 (Sec .2.3)

I think we should add a paragraph to explain that