I have the following snippet:
<snippet>
    <content><![CDATA[
{{#_}}${1:$SELECTION}{{/_}}
]]></content>
    <tabTrigger>i18n</tabTrigger>
    <!-- What can I put in scope? -->
    <scope>text.handlebars</scope>
</snippet>
But I only want it to be available within files that end in ".handlebars". I want to do this because I want to overload the i18n tab trigger for several different filetypes. Right now, I am stuck with renaming the tab trigger for this particular case.
This question is very useful for existing scopes: Defining scope for custom Sublime Text 2 snippets
 
     
    