The :command:`ascii_to_specint` tool reads a generic flux spectrum from an ASCII text file, and writes it to a :f-schema:`specint` file. It accepts the following command-line arguments:
.. program:: ascii_to_specint
.. option:: <ascii_file_name> Name of input ASCII text file (see below).
.. option:: <lam_units> Units of wavelength data in input file. Possible choices are :code:`'A'` (:math:`\angstrom`).
.. option:: <flux_units> Units of flux data in input file. Possible choices are :code:`'erg/cm^2/s/A'` (:math:`\erg\,\cm^{-2}\,\second^{-1}\,\angstrom^{-1}`).
.. option:: <specint_file_name> Name of output :f-schema:`specint` file.
.. option:: <label> (optional) Label of atmosphere parameter (must be accompanied by a corresponding :option:`<value>` argument).
.. option:: <value> (optional) Value of atmosphere parameter (must be accompanied by a corresponding :option:`<label>` argument).
Note that :option:`<label>` and :option:`<value>` parameters must be paired; and that there can be multiple of these pairs. The input ASCII text file should contain one or more lines, each consisting of a wavelength value followed by a flux value.