title: Multiple categories and series in Highcharts
body: <p>I have been working in an application to visualize in a single chart, multiple vertical profiles of data collected from moored buoys .</p>
  
  <p>An example of this kind of visualization looks like the following example <a href="https://jsfiddle.net/ordicu85/9g035cpo/" rel="nofollow noreferrer">https://jsfiddle.net/ordicu85/9g035cpo/</a> where the chart shows two vertical profiles of o2_concentration versus the related depth measurements.</p>
  
  <p>I need to solve the following issues:</p>
  
  <ol>
  <li><p>Show only a single vertical axis(depth) common for all active series in the legend. It should be adjusted automatically for all active series in teh legend.</p></li>
  <li><p>Normalize values in the vertical axis, like for example: 0, 10, 20, 30. 40...instead of all those decimal values.</p></li>
  </ol>
  
  <p>Here is the highchart code where categories represent depth measurements and series represent o2_concentration measurements.The first category corresponds to first data serie and the second category target the second data series:</p>
  
  <pre><code>let chart = Highcharts.chart('container', {
  chart: { type: "line", inverted: true, zoomType: "xy"
  },
  title: {
      text: 'o2 concentration vs depth'
  },
  xAxis: [
      {
       categories: [0.38, 1.02, 2.01, 3.06, 4.01, 5.05, 6, 7.05, 8.01, 9.02, 
      10.03, 11, 12.08, 13.04, 14.06, 15.07, 16.02, 17.04, 18.09, 19.03, 
      20.03, 21.04, 22.07, 23.04, 24.04, 25, 26, 27.05, 28.04, 29.06, 30.05], 
       reversed: true, title:{text:'depth'}
      },
      {
       categories: [0.37, 1.01, 2, 3, 4.03, 5.05, 6.03, 7, 8.02, 9.03, 10.01, 
       11.08, 12.03, 13.04, 14.06, 15.04, 16.01, 17, 18.03, 19.05, 20.01, 
       21.11, 22.07, 23.04, 24.09, 25.03, 26.03, 27.06, 28.01, 29.02, 30.07, 
       31, 32, 33.02, 34, 35.05, 36.02, 37.03, 38.04], reversed: true, title:
       {text:'depth'} 
      },
  ],
  yAxis: {
      title: {
          text: 'o2 concentration'
      }
  },
  
  series: [{
      name: 'Serie A',
      data: [  95.7, 82.7, 95.4, 96.5, 97.3, 98, 98.4, 98.8, 99.1, 99.4, 99.5, 
      99.6, 99.7, 99.8, 99.9, 100, 100.1, 100.2, 100.2, 100.2, 100.1, 100.1, 
      100, 99.9, 99.9, 100, 100.1, 100.2, 100.2, 100.3, 100.4],
      xAxis:0
  }, {
      name: 'Serie B',
      data: [96.7, 85.6, 92, 97.7, 98.1, 98.5, 98.9, 99.3, 99.6, 99.8, 100, 
      100.1, 100.2, 100.3, 100.4, 100.6, 100.9, 101.1, 101.2, 101.1, 101, 
      100.9, 100.9, 101, 101, 101, 101, 101.1, 101.1, 101.1, 101.1, 101.1, 
      101.1, 101.1, 101, 101, 100.9, 100.9, 100.9 ],
      xAxis:1
  }]
  </code></pre>
  
  <p>});</p>
  
  <p>Please, i would appreciate any help in those directions, i have been struggling for days with no success.</p>