[Solved]-A different suffix for each line on Highstock/Highcharts-Highcharts

i think this is what you want. you can specify the tooltip attribute on each series and use valuesuffix :

http://jsfiddle.net/axvcw/

        tooltip: {
            formatter : function() {
                 return this.y + ' ' +  this.series.tooltipoptions.valuesuffix;
            }
        },
        series: [{
            name: 'rainfall',
            type: 'column',
            yaxis: 1,
            data: [49.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
            tooltip: {
                valuesuffix: ' mm'
            }

        }, {
            name: 'temperature',
            type: 'spline',
            data: [7.0, 6.9, 9.5, 14.5, 18.2, 21.5, 25.2, 26.5, 23.3, 18.3, 13.9, 9.6],
            tooltip: {
                valuesuffix: '°c'
            }
        }]

modified from this demo: http://www.highcharts.com/demo/combo-dual-axes.

you don't need to provide the tooltip formatter function either, but if you wanted other than the default, that is how you could access the series valuesuffix.