Well, it's a report, the first part is the file, the second is the string, i searched the templates for all occurrences of style_array.mood.
so take this:
post_side.tpl:<img src="{$config.BASE_URL}/images/{$style_array.mood}/offline.gif" alt="{$lang.OFFLINE}" title="{$lang.OFFLINE}" />And you get that the template "post_side.tpl" contains the mood graphic "offline.gif".