#30 2-2-3 for unix won't compile, globals defined in multiple locations

[ptb]

change the four char * FOO declarations in eqn.h to extern char * FOO, like this:

extern char eqn_start_inline;
extern char eqn_end_inline;
extern char eqn_start_display;
extern char eqn_end_display;

Then put the (no extern!) char * FOO declarations in main.c. That defines the global variable containing the pointer in ONE place, not one zillion. One can fix this with compile flags too, but don't!

What you had defined the same global variables in each .c file in which eqn.h was included. Bad karma.