usgs maps -- xpdf crashes

[Warren Block]

On Tue, 1 Apr 2014, Gary Aitken wrote:

> Has anyone had any success downloading the usgs pdf versions of topo maps?
> After unzipping to get the pdf and feeding to xpdf,
> I get a core dump. (xpdf v3.03, fbsd 9.2)

Happens here, also.  The error is
   Syntax Error: Invalid OCG reference in OFF array in default viewing OCCD

No idea what that really means.  graphics/mupdf can display the same 
PDF.  Other viewers probably can also.