The VBM chunk contains the position, dimensions, and file name of an
ILBM image.

    struct VBMstruct {
        IEEE        XPos, YPos,     /* Virtual coords */
                    XSize, YSize,   /* Virtual size */
                    Rotation;       /* in degrees */
        USHORT      PathLen;        /* Length of dir path */
        char        Path[PathLen];  /* Null-terminated path of file */
    };

The coordinate (XPos, YPos) is the position of the upper left hand
corner of the bitmap and the XSize and YSize fields supply the x and y
dimensions to which the image should be scaled.  Rotation tells how
many degrees to rotate the ILBM around its upper left hand corner.
ProVector does not currently support rotation of bitmaps and will
ignore this value.  Path contains the name of the ILBM file and may
also contain a partial or full path to the file.  DR2D readers should
not assume the path is correct.  The full path to an ILBM on one
system may not match the path to the same ILBM on another system.  If
a DR2D reader cannot locate an ILBM file based on the full path name
or the file name itself (looking in the current directory), it should
ask the user where to find the image.