I suggest to try the search pattern "struct _[A-Z]+" on the source files. You will find a couple of places where names begin with an underscore and an uppercase letter.
Examples:
- __BIND_H
http://efte.svn.sourceforge.net/viewvc/efte/trunk/src/c_bind.h?revision=1112&view=markup
- __SYSDEP_H
http://efte.svn.sourceforge.net/viewvc/efte/trunk/src/sysdep.h?revision=1167&view=markup
This does not fit to the expected naming conventions of the C/C++ language standard.
http://en.wikipedia.org/wiki/Reserved_identifier
See also section "7.1.3 Reserved identifiers".
http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1124.pdf
Thank you for the suggestion. These were fixed in November 2010.