How to define theme translation file?

It all depends a bit if your current theme already supports localization.

Does your theme’s function file contain something like this?

load_theme_textdomain( 'twentytwelve', get_template_directory() . '/languages' );

If not, add it in there. And change twentytwelve to your theme-directory-name.

After that create a directory called languages in the root of your theme a drop your localization file (theme-directory-name-sv_SE.mo) in there.

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