sort:An unexpected result is displayed in the sort result.

[Yang Yanchao]

Dear Coreutils Maintainers,

When I sort the use cases using "sort":
[root@localhost test]# cat test 
1.2.v1.6
1.0.v3.5
1.10.v2.4
[root@localhost test]# sort -n -t'.' -k3,3 -k4,4 test
1.10.v2.4
1.0.v3.5
1.2.v1.6

The order I expected should be like this.
1.2.v1.6
1.10.v2.4
1.0.v3.5

It looks like the third column is alphabetic, and I added the -n option, which 
was ignored, but I used -k to specify the third column as the first 
priority.This means that -k has a lower priority than -n? Does this fit the 
intended design? 

Thanks,
Yang Yanchao