Addresses review comments

manual/source/classes/contributed_definitions/ellipsometry-structure.rst

@@ -114,14 +114,20 @@ There is a set of base classes for describing a dispersion.
  ``A`` and ``B`` are repeated parameters in the formula above.
 
  :ref:`NXdispersion_table`
- This describes a tabular dispersion where the dielectric function is an array versus wavelength or energy.
+ This describes a tabular dispersion where the permittivity is an array versus wavelength or energy.
 
 Formula Grammar
 ---------------
 
 Below you find a grammar to which the formula should adhere and which can be used to parse and
 evaluate the dispersion function. The terms ``single_param_name`` and ``param_name`` should be
 filled with the respective single and repeated params from the stored data.
+The grammer is written in the `EBNF <https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form>`_ dialect
+of `Lark <https://github.com/lark-parser/lark>`_, which is a parsing toolkit for python.
+It is easily translatable to general EBNF and other parser generator dialects.
+`Here <https://github.com/PyEllips/formula-dispersion>`_ is a reference implementation in Rust/Python with a
+`grammar <https://github.com/PyEllips/formula-dispersion/blob/main/src/formula_parser.lalrpop>`_
+written in `lalrpop <https://github.com/lalrpop/lalrpop>`_.
 
 .. code-block::