A question about samtools faidx

[WinterLi1993]

Dear Professor,
It's very glad to meet you here!
I have a question about Samtools faidx : what' the meanning of third and thirth and fifth cloumn in faidx result . like :
chr chr_length ? ? ?
1 249250621 3 60 61
2 243199373 253404805 60 61
3 198022430 500657504 60 61
4 191154276 701980311 60 61
5 180915260 896320495 60 61
6 171115067 1080251013 60 61
7 159138663 1254218001 60 61
8 146364022 1416008979 60 61
9 141213431 1564812405 60 61
10 135534747 1708379398 60 61
11 135006516 1846173062 60 61
12 133851895 1983429691 60 61
13 115169878 2119512455 60 61
14 107349540 2236601835 60 61
15 102531392 2345740538 60 61
16 90354753 2449980791 60 61
17 81195210 2541841461 60 61
18 78077248 2624389929 60 61
19 59128983 2703768469 60 61
20 63025520 2763882940 60 61
21 48129895 2827958890 60 61
22 51304566 2876890954 60 61
X 155270560 2929050600 60 61
Y 59373566 3086909006 60 61

Expecting your answers ! thank you !