How can I call this program?

From this link...http://www.midrangenews.com/view?id=2129. If I move the

prototype to another program and compile, I see that Pos & imgSize are 8
character Alpha.

I'm struggling to understand this code with the overlays and Const. It
seems like so much overkill to accept what amounts to 6 needed parameters.
(path, PDF name, top, left, height, width)

Thanks

H DFTACTGRP(*NO) ACTGRP(*NEW) OPTION(*SRCSTMT: *NODEBUGIO)
H THREAD(*SERIALIZE)
FPRTIMAGE O E PRINTER
D entryPList PR extpgm('PRTIMAGE')
D imageFile 128A Const Varying
D path 640A Const Varying
D pos Const LikeDS(POS_T)
D imgSize Const LikeDS(POS_T)
D entryPList PI
D imageFile 128A Const Varying
D path 640A Const Varying
D pos Const LikeDS(POS_T)
D imgSize Const LikeDS(POS_T)

D pos_T DS Qualified
D elem 5I 0
D top 5P 3
D left 5P 3
D width 5P 3 overlay(top)
D height 5P 3 overlay(left)
C MOVE *ON *INLR
/free
data = 'This is the Image Print Test program';
imgDown = pos.top;
imgAcross = pos.left;
imgWidth = imgSize.width;
imgHeight = imgSize.height;

imgFile = imageFile;
imgPath = path;
write image;
write text;
return;
/end-free