using Mono.CSharp; ... TypeDefinition td = new TypeDefinition ("MyType", null, null, null); FieldDefinition fd = new FieldDefinition ("myField", Modifiers.Public, new TypeReference (typeof(int))); td.Fields.Add (fd);In this example, we create a new `TypeDefinition` representing a new type named "MyType". Next, we create a new `FieldDefinition` representing a new field named "myField" with the `public` access modifier and a type of `int`. Finally, we add the field to the type's `Fields` collection. Package/Library: Mono.CSharp This example uses the `Mono.CSharp.FieldDefinition` and `Mono.CSharp.TypeDefinition` classes, both of which are part of the Mono.CSharp library. Therefore, the package/library being used in this example is Mono.CSharp.