1Exuberant ctags generates following tags file 2 3 $ ctags -o - --C-kinds='x' input.h 4 C /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^class C;$/;" x 5 S /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^struct S;$/;" x 6 a /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^extern int a;$/;" x 7 b /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^extern struct B b;$/;" x 8 9Universal ctags generates following tags file 10 11 $ ./ctags -o - --kinds-C='x' input.h 12 a /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^extern int a;$/;" x typeref:typename:int 13 b /home/jet/var/ctags/Units/review-needed.r/extern_variable.h.t/input.h /^extern struct B b;$/;" x typeref:struct:B 14 15I marked this .b. We have to consider which behavior is better. 16