%!PS-Adobe-2.0
%%Title: Blue Book Program 2, on page 135
%%Creator: Adobe Systems Incorporated 
%%CreationDate: Thu Dec 28 13:15:44 PST 1989
%%EndComments

/inch {72 mul} def
/centersquare
	{
	newpath
	.5 .5 moveto  -.5 .5 lineto
	-.5 -.5 lineto  .5 -.5 lineto
	closepath
	} def
	
gsave
  2.5 inch 6 inch translate
  1 16 div setlinewidth
  1 1 5
	{ gsave
	    .5 mul inch dup scale
	    centersquare stroke
	  grestore
	} for
grestore

gsave
  6 inch 6 inch translate
  1 setlinewidth
  /cmtx matrix currentmatrix def
  1 1 5
	{ gsave
	    .5 mul inch dup scale
	    centersquare
	    cmtx setmatrix 
	    stroke
	  grestore
	} for
grestore

showpage
% But what does it do?