When creating child theme, I must write like this.
/*
Theme Name: 2012 Child
Template: twentytwelve
*/
Is that Template
name is always same as directory name?
Or is it defined somewhere else?
According to the codex
The Template is the directory name of the parent theme
... If you want to make a child of a theme with the directory name example-theme-name, then you would use Template: example-theme-name.
So yes its always the name of the parent theme directory.