<varlistentry>
  <term><option>-h</option></term>
  <term><option>--help</option></term>
  <listitem>
    <simpara>Print a short help message describing command line
    options to standard output and exit</simpara>
  </listitem>
</varlistentry>

<varlistentry>
  <term><option>--version</option></term>
  <listitem>
    <simpara>Print program version information to standard output and
    exit</simpara>
  </listitem>
</varlistentry>

<varlistentry>
  <term><option>-v</option></term>
  <term><option>--verbose<optional>=<replaceable
          class="parameter">n</replaceable></optional></option></term>
  <listitem>
    <simpara>Increase debug output level.  Multiple
      <option>-v</option> options create more spew.  Alternatively
      specify <replaceable class="parameter">n</replaceable> to
      set the debug level directly
    </simpara>
  </listitem>
</varlistentry>

<varlistentry>
  <term><option>-S<optional><replaceable
          class="parameter">symbology</replaceable>.</optional><replaceable
        class="parameter">config</replaceable><optional>=<replaceable
          class="parameter">value</replaceable></optional></option></term>
  <term><option>--set <optional><replaceable
          class="parameter">symbology</replaceable>.</optional><replaceable
        class="parameter">config</replaceable><optional>=<replaceable
          class="parameter">value</replaceable></optional></option></term>
  <listitem>
    <simpara>Set decoder configuration option <replaceable
      class="parameter">config</replaceable> for <replaceable
      class="parameter">symbology</replaceable> to <replaceable
      class="parameter">value</replaceable>.  <replaceable
      class="parameter">value</replaceable> defaults to 1 if omitted.
      <replaceable class="parameter">symbology</replaceable> is one of
      <option>ean13</option>, <option>ean8</option>,
      <option>upca</option>, <option>upce</option>,
      <option>isbn13</option>, <option>isbn10</option>,
      <option>i25</option>, <option>code39</option>,
      <option>code128</option> or the special value <option>*</option>.
      If <replaceable class="parameter">symbology</replaceable> is
      omitted or <option>*</option>, the <replaceable
      class="parameter">config</replaceable> will be set for all
      applicable symbologies.  These are the currently recognized
      <replaceable class="parameter">config</replaceable>s.  Prefix a
      config with "no-" to negate it.  Not all configs are appropriate
      for every symbology.</simpara>

    <variablelist>
      <varlistentry>
        <term><option>enable</option></term>
        <listitem>
          <simpara>Control decoding/reporting of a symbology.  For
            symbologies which are just subsets of <option>ean13</option>
            (<option>upca</option>, <option>upce</option>,
            <option>isbn13</option>, <option>isbn10</option>), this
            config controls whether the subsets are detected and
            reported as such.  These special cases are disabled by
            default, all other symbologies default to enabled</simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>disable</option></term>
        <listitem>
          <simpara>Antonym for <option>enable</option></simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>emit-check</option></term>
        <listitem>
          <simpara>Control whether check digits are included in the
            decoded output.  Enabled by default.  This config does not
            apply for <option>code128</option>, which never returns the
            check digit.  It also not apply for cases where the check
            digit is disabled (see <option>add-check</option>).  Check
            digits are currently not implemented for
            <option>i25</option> or <option>code39</option></simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>add-check</option></term>
        <listitem>
          <simpara>Enable decode and verification of a check digit for
            symbologies where it is optional: this will include
            <option>code39</option> and <option>i25</option>, neither of
            which implements the check digit yet</simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>ascii</option></term>
        <listitem>
          <simpara>Enable escape sequences that encode the full ASCII
            character set.  This would apply to <option>code39</option>,
            except that it's not implemented either...</simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>position</option></term>
        <listitem>
          <simpara>Enable collection of symbol position information.
          Enabled by default.  Currently, the position information is
          unusable, so you can save a few cycles by disabling
          this.</simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>min-length=<replaceable class="parameter">n</replaceable></option></term>
        <term><option>max-length=<replaceable class="parameter">n</replaceable></option></term>
        <listitem>
          <simpara>Bound the number of decoded characters in a valid symbol.
          If a decode result is outside the configured min/max range
          (inclusive), it will not be reported.  Set to 0 to disable the
          corresponding check.  This setting applies to variable-length
          symbologies: <option>i25</option>, <option>code39</option>,
          <option>code128</option> and <option>pdf417</option>.
          <option>min-length</option> defaults to 6 for <option>i25</option>
          and 1 for <option>code39</option> (per Code 39 autodiscrimination
          recommendation); all others default to 0</simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>x-density=<replaceable class="parameter">n</replaceable></option></term>
        <term><option>y-density=<replaceable class="parameter">n</replaceable></option></term>
        <listitem>
          <simpara>Adjust the density of the scanner passes.  Lower values
          scan more of the image at the cost of decreased performance.
          Setting to 0 disables scanning along that axis.  Defaults are both
          1.</simpara>
        </listitem>
      </varlistentry>
    </variablelist>

  </listitem>
</varlistentry>
