What's the proper use of the Equestria Girls tag?

Should the Equestria Girls tag be used whenever there is something in the picture from or referencing Equestria Girls (such as scenes, characters etc.) or should it only be used when the art is depicting direct scenes, references or spoilers from the movies? I don’t know so I’d like to know.

@yttyr
 
Actually the tag is simultaneously used to refer to the series in general, the first film in it and the character designs in it.

@Mildgyth  
Ok, then it’s used as I thought it was. Thanks!