The mediaobject element (and inlinemediaobject) can contain several, alternative objects. The $mediaobject-exclude-extensions parameter provides a way to exclude some of them.

One common use case is to provide two versions of each image, one as a bitmap, perhaps a PNG, and another as a vector, perhaps an EPS. Then $mediaobject-exclude-extensions can be used to exclude “.eps” images from the web format and “.png” images from the print (or paged media) format.