I must delete this question because of administrator who manages war game site.
But I can't delete because of answers.. so I had no choice but to blind this question.
The solution is this:
It works because PHP replaces dots and spaces with underscores in the keys of the request data arrays (
From PHP docs:
Note: Dots and spaces in variable names are converted to underscores. For example
<input name="a.b" />becomes
This is probably a relic from times when register globals was still a thing.