[XtraChartsLocalizableCategory(XtraChartsCategory.Behavior)]
public string ToolTipPointPattern { get; set; }

<XtraChartsLocalizableCategory(XtraChartsCategory.Behavior)>
Public Property ToolTipPointPattern As String

using DevExpress.XtraCharts;
using System;
using System.Windows.Forms;
using DevExpress.Utils;
using System.Collections.Generic;
using System.Data;

namespace TooltipCustomization {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }
        // Create a data source.  
        public class TestChartData {
            public string Argument { get; set; }
            public double Value { get; set; }
            public string Comment { get; set; }
            public TestChartData(string arguments, double value, string comment) {
                Argument = arguments;
                Value = value;
                Comment = comment;
            }

        }
        private List<TestChartData> CreateChartData() {
            var list = new List<TestChartData>();
            list.Add(new TestChartData("A", 4, "comment for A"));
            list.Add(new TestChartData("B", 2, "comment for B"));
            list.Add(new TestChartData("C", 17, "comment for C"));
            list.Add(new TestChartData("D", 4, "comment for D"));
            list.Add(new TestChartData("E", 17, "comment for E"));
            list.Add(new TestChartData("F", 12, "comment for F"));
            list.Add(new TestChartData("G", 15, "comment for G"));
            return list;
        }

        private void Form1_Load(object sender, EventArgs e) {
            // Create an empty chart.
            ChartControl chartControl = new ChartControl();

            // Add the chart to the form.
            chartControl.Dock = DockStyle.Fill;
            this.Controls.Add(chartControl);

            // Create a series and add points to it.
            Series boundSeries = new Series("Bound Series", ViewType.Line);
            // Assign the created data source to the series.
            boundSeries.DataSource = CreateChartData();
            boundSeries.ArgumentScaleType = ScaleType.Auto;
            boundSeries.ArgumentDataMember = "Argument";
            boundSeries.ValueScaleType = ScaleType.Numerical;
            boundSeries.ValueDataMembers.AddRange(new string[] { "Value" });

            Series unboundSeries = new Series("Unbound Series", ViewType.Line);
            unboundSeries.Points.Add(new SeriesPoint("A", new double[] { 9 }));
            unboundSeries.Points.Add(new SeriesPoint("B", new double[] { 7 }));
            unboundSeries.Points.Add(new SeriesPoint("C", new double[] { 23 }));
            unboundSeries.Points.Add(new SeriesPoint("D", new double[] { 9 }));
            unboundSeries.Points.Add(new SeriesPoint("E", new double[] { 23 }));
            unboundSeries.Points.Add(new SeriesPoint("F", new double[] { 17 }));
            unboundSeries.Points.Add(new SeriesPoint("G", new double[] { 20 }));

            Series unboundSeriesWithTag = new Series("Unbound Series with Tag", ViewType.Line);
            unboundSeriesWithTag.Points.Add(new SeriesPoint("A", 2) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("B", 0) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("C", 15) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("D", 2) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("E", 15) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("F", 10) { Tag = new { Test = "TestValue" } });
            unboundSeriesWithTag.Points.Add(new SeriesPoint("G", 13) { Tag = new { Test = "TestValue" } });

            // Add the series to the chart.
            chartControl.Series.AddRange(unboundSeries, unboundSeriesWithTag, boundSeries);
            // Enable data point markers.
            ((LineSeriesView)unboundSeries.View).MarkerVisibility = DefaultBoolean.True;
            ((LineSeriesView)unboundSeriesWithTag.View).MarkerVisibility = DefaultBoolean.True;
            ((LineSeriesView)boundSeries.View).MarkerVisibility = DefaultBoolean.True;
            // Disable a crosshair cursor.
            chartControl.CrosshairEnabled = DefaultBoolean.False;

            // Enable chart tooltips. 
            chartControl.ToolTipEnabled = DefaultBoolean.True;

            // Show a tooltip's beak.
            ToolTipController controller = new ToolTipController();
            chartControl.ToolTipController = controller;
            controller.ShowBeak = true;

            // Change the default tooltip mouse position to relative position.
            ToolTipRelativePosition relativePosition = new ToolTipRelativePosition();
            chartControl.ToolTipOptions.ToolTipPosition = relativePosition;

            // Specify the tooltip relative position offsets.  
            relativePosition.OffsetX = 2;
            relativePosition.OffsetY = 2;

            // Specify the tooltip point pattern.
            unboundSeries.ToolTipPointPattern = "Line Series: {A}:{V}";
            unboundSeriesWithTag.ToolTipPointPattern = "{A}: {V} ({Test})";
            boundSeries.ToolTipPointPattern = "{A}: {V} ({Comment})";
        }
    }
}

Imports DevExpress.XtraCharts
Imports System
Imports System.Windows.Forms
Imports DevExpress.Utils
Imports System.Collections.Generic
Imports System.Data

Namespace TooltipCustomization
    Partial Public Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
        End Sub
        ' Create a data source.  
        Public Class TestChartData
            Public Property Argument() As String
            Public Property Value() As Double
            Public Property Comment() As String
            Public Sub New(ByVal arguments As String, ByVal value As Double, ByVal comment As String)
                Argument = arguments
                Me.Value = value
                Me.Comment = comment
            End Sub

        End Class
        Private Function CreateChartData() As List(Of TestChartData)
            Dim list = New List(Of TestChartData)()
            list.Add(New TestChartData("A", 4, "comment for A"))
            list.Add(New TestChartData("B", 2, "comment for B"))
            list.Add(New TestChartData("C", 17, "comment for C"))
            list.Add(New TestChartData("D", 4, "comment for D"))
            list.Add(New TestChartData("E", 17, "comment for E"))
            list.Add(New TestChartData("F", 12, "comment for F"))
            list.Add(New TestChartData("G", 15, "comment for G"))
            Return list
        End Function

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
            ' Create an empty chart.
            Dim chartControl As New ChartControl()

            ' Add the chart to the form.
            chartControl.Dock = DockStyle.Fill
            Me.Controls.Add(chartControl)

            ' Create a series and add points to it.
            Dim boundSeries As New Series("Bound Series", ViewType.Line)
            ' Assign the created data source to the series.
            boundSeries.DataSource = CreateChartData()
            boundSeries.ArgumentScaleType = ScaleType.Auto
            boundSeries.ArgumentDataMember = "Argument"
            boundSeries.ValueScaleType = ScaleType.Numerical
            boundSeries.ValueDataMembers.AddRange(New String() { "Value" })

            Dim unboundSeries As New Series("Unbound Series", ViewType.Line)
            unboundSeries.Points.Add(New SeriesPoint("A", New Double() { 9 }))
            unboundSeries.Points.Add(New SeriesPoint("B", New Double() { 7 }))
            unboundSeries.Points.Add(New SeriesPoint("C", New Double() { 23 }))
            unboundSeries.Points.Add(New SeriesPoint("D", New Double() { 9 }))
            unboundSeries.Points.Add(New SeriesPoint("E", New Double() { 23 }))
            unboundSeries.Points.Add(New SeriesPoint("F", New Double() { 17 }))
            unboundSeries.Points.Add(New SeriesPoint("G", New Double() { 20 }))

            Dim unboundSeriesWithTag As New Series("Unbound Series with Tag", ViewType.Line)
            unboundSeriesWithTag.Points.Add(New SeriesPoint("A", 2) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("B", 0) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("C", 15) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("D", 2) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("E", 15) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("F", 10) With {
                .Tag = New With {Key .Test = "TestValue"}
            })
            unboundSeriesWithTag.Points.Add(New SeriesPoint("G", 13) With {
                .Tag = New With {Key .Test = "TestValue"}
            })

            ' Add the series to the chart.
            chartControl.Series.AddRange(unboundSeries, unboundSeriesWithTag, boundSeries)
            ' Enable data point markers.
            CType(unboundSeries.View, LineSeriesView).MarkerVisibility = DefaultBoolean.True
            CType(unboundSeriesWithTag.View, LineSeriesView).MarkerVisibility = DefaultBoolean.True
            CType(boundSeries.View, LineSeriesView).MarkerVisibility = DefaultBoolean.True
            ' Disable a crosshair cursor.
            chartControl.CrosshairEnabled = DefaultBoolean.False

            ' Enable chart tooltips. 
            chartControl.ToolTipEnabled = DefaultBoolean.True

            ' Show a tooltip's beak.
            Dim controller As New ToolTipController()
            chartControl.ToolTipController = controller
            controller.ShowBeak = True

            ' Change the default tooltip mouse position to relative position.
            Dim relativePosition As New ToolTipRelativePosition()
            chartControl.ToolTipOptions.ToolTipPosition = relativePosition

            ' Specify the tooltip relative position offsets.  
            relativePosition.OffsetX = 2
            relativePosition.OffsetY = 2

            ' Specify the tooltip point pattern.
            unboundSeries.ToolTipPointPattern = "Line Series: {A}:{V}"
            unboundSeriesWithTag.ToolTipPointPattern = "{A}: {V} ({Test})"
            boundSeries.ToolTipPointPattern = "{A}: {V} ({Comment})"
        End Sub
    End Class
End Namespace

chart.SeriesTemplate.ToolTipPointPattern = "{S}: {A} ({VP:P})";
chart.SeriesTemplate.SeriesPointsSorting = SortingMode.Ascending;

Me.chart.SeriesTemplate.ValueDataMembers.AddRange("Value")
Me.chart.SeriesTemplate.ToolTipPointPattern = "{S}: {A} ({VP:P})"
Me.chart.SeriesTemplate.SeriesPointsSorting = DevExpress.XtraCharts.SortingMode.Ascending