疑问？？？？

root@hbg:/# iw phy phy0 info
Wiphy phy0
max # scan SSIDs: 4
max scan IEs length: 2257 bytes
Retry short limit: 7
Retry long limit: 4
Coverage class: 5 (up to 2250m) // 这个是用来干嘛的，等级是如何划分的？
Device supports AP-side u-APSD.
Device supports T-DLS.
Available Antennas: TX 0x3 RX 0x3
Configured Antennas: TX 0x1 RX 0x1
Supported interface modes:
* IBSS
* managed
* AP
* AP/VLAN
* WDS
* monitor
* mesh point
* P2P-client
* P2P-GO
Band 1:
Capabilities: 0x11ef
RX LDPC
HT20/HT40
SM Power Save disabled
RX HT20 SGI
RX HT40 SGI
TX STBC
RX STBC 1-stream
Max AMSDU length: 3839 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 8 usec (0x06)
HT TX/RX MCS rate indexes supported: 0-7
Frequencies:
* 2412 MHz [1] (19.0 dBm)
* 2417 MHz [2] (19.0 dBm)
* 2422 MHz [3] (19.0 dBm)
* 2427 MHz [4] (19.0 dBm)
* 2432 MHz [5] (19.0 dBm)
* 2437 MHz [6] (19.0 dBm)
* 2442 MHz [7] (19.0 dBm)
* 2447 MHz [8] (19.0 dBm)
* 2452 MHz [9] (19.0 dBm)
* 2457 MHz [10] (19.0 dBm)
* 2462 MHz [11] (19.0 dBm)
* 2467 MHz [12] (disabled)
* 2472 MHz [13] (disabled)
* 2484 MHz [14] (disabled)
valid interface combinations:
* #{ managed } <= 2048, #{ AP, mesh point } <= 8, #{ P2P-client, P2P-GO } <= 1, #{ IBSS } <= 1,
total <= 2048, #channels <= 1, STA/AP BI must match
* #{ WDS } <= 2048,
total <= 2048, #channels <= 1, STA/AP BI must match
* #{ IBSS, AP, mesh point } <= 1,
total <= 1, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz }

HT Capability overrides:
* MCS: ff ff ff ff ff ff ff ff ff ff
* maximum A-MSDU length
* supported channel width
* short GI for 40 MHz
* max A-MPDU length exponent
* min MPDU start spacing
root@hbg:/#