// Create new project
Project project = new Project("New Project.mpp");

// Create an Extended Attribute Definition of Text1 type
var taskExtendedAttributeText1Definition = ExtendedAttributeDefinition.CreateTaskDefinition(CustomFieldType.Text, ExtendedAttributeTask.Text1, "Task City Name");

// Add it to the project's Extended Attributes collection
project.ExtendedAttributes.Add(taskExtendedAttributeText1Definition);

// Add a task to the project
Task task = project.RootTask.Children.Add("Task 1");

// Create an Extended Attribute from the Attribute Definition
var taskExtendedAttributeText1 = taskExtendedAttributeText1Definition.CreateExtendedAttribute();

// Assign a value to the generated Extended Attribute. The type of the attribute is "Text", the "TextValue" property should be used.
taskExtendedAttributeText1.TextValue = "London";

// Add the Extended Attribute to task
task.ExtendedAttributes.Add(taskExtendedAttributeText1);

project.Save("PlainTextExtendedAttribute_out.mpp", SaveFileFormat.MPP);

Project project = new Project("New Project.mpp");

// Create an Extended Attribute Definition of Text2 type
var taskExtendedAttributeText2Definition = ExtendedAttributeDefinition.CreateLookupTaskDefinition(CustomFieldType.Text, ExtendedAttributeTask.Text2, "Task Towns Name");

// Add lookup values for the extended attribute definition
taskExtendedAttributeText2Definition.AddLookupValue(new Value { Id = 1, StringValue = "Town1", Description = "This is Town1" });
taskExtendedAttributeText2Definition.AddLookupValue(new Value { Id = 2, StringValue = "Town2", Description = "This is Town2" });

// Add it to the project's Extended Attributes collection
project.ExtendedAttributes.Add(taskExtendedAttributeText2Definition);

// Add a task to the project
var task2 = project.RootTask.Children.Add("Task 2");

// Crate an Extended Attribute from the Text2 Lookup Definition for Id 1
var taskExtendedAttributeText2 = taskExtendedAttributeText2Definition.CreateExtendedAttribute(taskExtendedAttributeText2Definition.ValueList[1]);

// Add the Extended Attribute to task
task2.ExtendedAttributes.Add(taskExtendedAttributeText2);

project.Save("TextExtendedAttributeWithLookup_out.mpp", SaveFileFormat.MPP);

Project project2 = new Project("New Project.mpp");

// Create an Extended Attribute Definition of Duration2 type
var taskExtendedAttributeDuration2Definition = ExtendedAttributeDefinition.CreateLookupTaskDefinition(CustomFieldType.Duration, ExtendedAttributeTask.Duration2, "Some duration");

// Add lookup values for extended attribute definition
taskExtendedAttributeDuration2Definition.AddLookupValue(new Value { Id = 2, Duration = project2.GetDuration(4, TimeUnitType.Hour), Description = "4 hours" });
taskExtendedAttributeDuration2Definition.AddLookupValue(new Value { Id = 3, Duration = project2.GetDuration(1, TimeUnitType.Day), Description = "1 day" });
taskExtendedAttributeDuration2Definition.AddLookupValue(new Value { Id = 4, Duration = project2.GetDuration(1, TimeUnitType.Hour), Description = "1 hour" });
taskExtendedAttributeDuration2Definition.AddLookupValue(new Value { Id = 7, Duration = project2.GetDuration(10, TimeUnitType.Day), Description = "10 days" });

// Add the definition to the project's Extended Attributes collection
project2.ExtendedAttributes.Add(taskExtendedAttributeDuration2Definition);

// Add a task to the project
var task3 = project2.RootTask.Children.Add("Task 3");

// Create an Extended Attribute from the Duration2 Lookup Definition for Id 3
var taskExtendedAttributeDuration2 = taskExtendedAttributeDuration2Definition.CreateExtendedAttribute(taskExtendedAttributeDuration2Definition.ValueList[3]);

// Add the Extended Attribute to task
task3.ExtendedAttributes.Add(taskExtendedAttributeDuration2);

project2.Save("DurationExtendedAttributeWithLookup_out.mpp", SaveFileFormat.MPP);

Project project3 = new Project("New Project.mpp");

// Create an Extended Attribute Definition of Finish2 Type
var taskExtendedAttributeFinish2Definition = ExtendedAttributeDefinition.CreateLookupTaskDefinition(CustomFieldType.Finish, ExtendedAttributeTask.Finish2, "Some finish");

// Add lookup values for extended attribute defintion
taskExtendedAttributeFinish2Definition.AddLookupValue(new Value { Id = 2, DateTimeValue = new DateTime(1984, 01, 01, 00, 00, 01), Description = "This is Value2" });
taskExtendedAttributeFinish2Definition.AddLookupValue(new Value { Id = 3, DateTimeValue = new DateTime(1994, 01, 01, 00, 01, 01), Description = "This is Value3" });
taskExtendedAttributeFinish2Definition.AddLookupValue(new Value { Id = 4, DateTimeValue = new DateTime(2009, 12, 31, 00, 00, 00), Description = "This is Value4" });
taskExtendedAttributeFinish2Definition.AddLookupValue(new Value { Id = 7, DateTimeValue = DateTime.Now, Description = "This is Value6" });

// Add the definition to the project's Extended Attributes collection
project3.ExtendedAttributes.Add(taskExtendedAttributeFinish2Definition);

// Add a task to the project
var task4 = project3.RootTask.Children.Add("Task 4");

// Create an Extended Attribute from the Finish2 Lookup Definition for Id 3
var taskExtendedAttributeFinish2 = taskExtendedAttributeFinish2Definition.CreateExtendedAttribute(taskExtendedAttributeFinish2Definition.ValueList[3]);

// Add the Extended Attribute to task
task4.ExtendedAttributes.Add(taskExtendedAttributeFinish2);

project3.Save("FinishExtendedAttributeWithLookup_out.mpp", SaveFileFormat.MPP);