Help with etags

["N. Raghavendra" <nyraghu27132@gmail.com>]

I am trying to build a tags table for some files which look like this

------------------------File: Homotopies.v ---------------------------
Require Export Paths.

Definition
  homotopies
  {X Y : U} (f g : X -> Y)
  : U
  := prod (x : X) , (paths (f x) (g x)).

Notation
  "f ~ g"
  := (homotopies f g).

Definition
  function_induced_function_homotopic_identity
  {X : U} (f : X -> X) (h : f ~ (Functions.identity X)) (x y : X)
  (p : paths x y)
  : paths ((induced_function f p) @ (h y)) ((h x) @ p).
----------------------------------------------------------------------

I want the tags table to show the identifier in every line following a
line containing `Definition', e.g., `homotopies' and
`function_induced_function_homotopic_identity'.

I tried the command

etags --language=none --regex="/^[[:space:]]*Definition[[:space:]\n]+[[:space:]]*\([[:alnum:]_]+\)[[:space:]]*\n/\1/" Homotopies.v

but am getting an empty tags table.  What is the right way to generate
tags for such files?

Thanks,
Raghu.

--
N. Raghavendra <raghu@hri.res.in>, http://www.retrotexts.net/
Harish-Chandra Research Institute, http://www.hri.res.in/