FileRefhas attributes that are available during page templating and rendering (in page context). This operation collects attributes from various locations.
__.jsin the same folder where file is. Difference from single-underscored attribute files (explained above) is that they are only applied to the same folder, and not child folders. They are shared only by files in the same folder.
<filename>_.jsonthe same as for double-underscored attributes; but they are not shared.