The ImageShadow member is a pointer to the shadow mask of a Bob. A shadow mask is the logical or of all bitplanes of a Bob image. The system uses the shadow mask in conjunction with PlaneOnOff, discussed below, for color selection. It also uses the shadow mask to "cookie cut" the bits that will be overwritten by this Bob, to save and later restore the background. The following figure shows the shadow mask of the image described above. mem + 0 1111 1111 1111 1111 Shadow mask for line 1 mem + 1 0011 1100 0011 1100 Shadow mask for line 2 mem + 2 0000 1111 1111 0000 Shadow mask for line 3 mem + 3 0000 0011 1100 0000 Shadow mask for line 4 mem + 4 0000 0001 1000 0000 Shadow mask for line 5 Space for the ImageShadow must be provided and this pointer initialized to point to it. The amount of memory needed is equivalent to one plane of the image: shadow_size = myBob->BobVSprite->Height * myBob->BobVSprite->Width; The example image is 5 high and 1 word wide, so, 5 words must be made available. Note: ----- The ImageShadow memory must be allocated from Chip memory (MEMF_CHIP).