UML Class Diagram

In software engineering, a class diagram in the Unified Modeling Language (UML), is a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, and the relationships between the classes.
The UML specifies two types of scope for members: instance and classifier[1]. In the case of instance members, the scope is a specific instance. For attributes, it means that its value can vary between instances. For methods, it means that its invocation affects the instance state, in other words, affects the instance attributes. Otherwise, in the classifier member, the scope is the class. For attributes, it means that its value is equal for all instances. For methods, it means that its invocation do not affect the instance state. Classifier members are commonly recognized as "static" in many programming languages. To indicate that a member has the classifier scope, its name must be underlined. Otherwise, as default, the instance scope is considered.

OpenFileDialog

Prompts the user to open a file. This class cannot be inherited
This class allows you to check whether a file exists and to open it. The show read only property determines whether a read-only check box appears in the dialog box. The ReadOnlyChecked property indicates whether the read-only check box is checked.
Most of the functionality for this class is found in the FileDialog class.
If you want to give the user the ability to select a folder instead of a file, use FolderBrowserDialog instead. The following code example creates an OpenFileDialog, sets several properties, and displays the dialog box using the CommonDialog..::.ShowDialog method. The example requires a form with a Button placed on it and the System.IO namespace added to it.