Hello World, 

Acrobat 5 has problems with reading files that use forms with check fields
and use /DV (On) and /DV (Off) default values. 

Context happens to write default values as such, while acrobat 5 is only
happy with /DV /On

BTW, reading the specs and using acro4 to create a test file does not realy
help, since Yes No On and Off may happily be mixed with Foo and Bar (since
these are only placeholders).   

You can clean up files using the following perl script: 

-----------------------------------------------------------------------
$pdffile = $ARGV[0] ; 

exit unless              -e $pdffile       ; 
exit unless open (PDFINP, "<$pdffile")     ; binmode PDFINP ; 
exit unless open (PDFOUT, ">$pdffile.new") ; binmode PDFOUT ; 

$found = 0 ; 

while (<PDFINP>) 
  { if (s"(/Subtype\s*/Widget.*?/FT\s*/Btn.*?/DV\s*)\((.*?)\)"$1/$2 "gmois)
      { $found = 1 }  
    print PDFOUT $_ }   

close (PDFINP) ; 
close (PDFOUT) ; 

unlink "$pdffile.new" unless $found ; 
-----------------------------------------------------------------------

for non context files, you may need to change the regexp.

If you want to patch spec-fdf.tex, here you go: in 

  \doFDFpresetchoicefield 

locate 

  /DV (\FDFDefault)

and change this (2 times) into 

  /DV /\FDFDefault\space

Since this is a runtime loaded driver file, you don';t need to compile a
format, 

[took me a whole sunny sunday afternoon to locate this bug, and i really
don't look forward to cleaning up all my files]

The attached file should work on pdf 5 viewers and demonstrate a new
javascript trick, in order to start the demo, click on the page border. 

Hans