How to use markline, with category X-axis ?

问题简述 (One-line summary)

How to draw a line using markline at specific Y-axis value in a line graph

版本及环境 (Version & Environment)

• ECharts 3.0 (ECharts version):
• Google chrome (Browser version):
• OS X (OS Version):

重现步骤 (Steps to reproduce)

1. open this echarts example
2. use the below options

option = {
    title: {
        text: '未来一周气温变化',
        subtext: '纯属虚构'
    },
    tooltip: {
        trigger: 'axis'
    },
    legend: {
        data:['最高气温','最低气温']
    },
    toolbox: {
        show: true,
        feature: {
            dataZoom: {},
            dataView: {readOnly: false},
            magicType: {type: ['line', 'bar']},
            restore: {},
            saveAsImage: {}
        }
    },
    xAxis:  {
        type: 'category',
        boundaryGap: false,
        data: ['周一','周二','周三','周四','周五','周六','周日']
    },
    yAxis: {
        type: 'value',
        axisLabel: {
            formatter: '{value} °C'
        }
    },
    series: [
        {
            name:'最高气温',
            type:'line',
            data:[11, 11, 15, 13, 12, 13, 10],
            markPoint: {
                data: [
                    {type: 'max', name: '最大值'},
                    {type: 'min', name: '最小值'}
                ]
            },
            markLine: {
                data: [
                    {
                        name : "Test",
                        x : 0,
                        y : 11
                    },{
                        name :"Test",
                        x: MAXNUMBER,
                        y : 11
                    }
                ]
            }
        },
        {
            name:'最低气温',
            type:'line',
            data:[1, -2, 2, 5, 3, 2, 0],
            markPoint: {
                data: [
                    {name: '周最低', value: -2, xAxis: 1, yAxis: -1.5}
                ]
            },
            markLine: {
                data: [
                    {type: 'average', name: '平均值'}
                ]
            }
        }
    ]
};

期望结果 (Expected behaviour)

markLine: {
                data: [
                    {
                        name : "Test",
                        x : 0,
                        y : 11
                    },{
                        name :"Test",
                        x: MAXNUMBER,
                        y : 11
                    }
                ]
            }

markline should draw a line at Y-axis value 11. But it is not working. It is not clear from the documentation about how to use the markline when X-axis is of category type.

可能哪里有问题 (What went wrong)

ECharts配置项 (ECharts option)

Same as it is provided in steps-to-reproduce section.

其他信息 (Other comments)