first page puzzle

[Alan Bowen <acbowen@princeton.edu>]

The following code

	\setuphead[chapter][page=yes]	
	\setuppagenumbering[alternative=doublesided]
	\setuppagenumbering[location={header, middle},state=nomarking]
	\installpagebreakhandler{last}{} 	

	\definehead[Item][title]
	\setupsectionblock[Item][number=no,page=right]
	\setuphead[Item][after={\blank[2*big]},alternative=middle,style={\tfa 
\rm}]

	\setuphead[Item][header=high,footer={}]
	\setupheadertexts[text]
		[{\sc\ItemTitle}]
		[\pagenumber]
		[\pagenumber]
		[{\it xxxxx}]

produces no header or footer on the first page, just as I want, in a  
multi-page document. What I am not seeing is why the same code  
produces a header (“ItemTitle....pagenumber”) when the document is  
only one page in length.

I realize that I can insert \setupheader[state=high] in the source  
file of my single-page documents to get what I want, but that would  
still leave me puzzled.

Any suggestions/explanations would be much appreciated.

Alan