When you load a vector image using LoadBGPic() or @BGPIC, you will get a
special type of BGPic: a vector BGPic. When loading normal images like PNG,
JPEG, etc. you will always get a raster BGPic. You can find out the type of
a BGPic by querying the #ATTRTYPE attribute using GetAttribute().
The advantage of a vector BGPic is that you can scale and/or transform it without any quality losses. For example, when the user resizes a display, its BGPic can be adapted to the new size without quality sacrifices. So it is possible to create scripts which are infinitely scalable. All you have to do is stick to vector BGPics, vector brushes, and vector text (i.e. use TrueType fonts).
Besides vector BGPics generated from vector image formats, there are also some other types of vector BGPics in Hollywood. For example, the CreateGradientBGPic() and CreateTexturedBGPic() functions will also create vector BGPics that can be infinitely scaled.