AutoCAD .NET API基础（一） AutoCAD 对象层次结构（2）

2、The Document Object Document对象
The Document object, which is actually an AutoCAD drawing, is part of the DocumentCollection object and provides access to the Database object which is associated with the Document object. The Database object contains all of the graphical and most of the nongraphical AutoCAD objects. For more information on the Database object, see The Database Object.
Document对象，实际上就是一个AutoCAD图形，是DocumentCollection对象的一部分，提供了访问与Document对象相关联的Database对象的功能。Database对象包含AutoCAD全部的图形对象和大部分非图形对象。Database对象的更多信息参见Database对象。
Along with the Database object, the Document object provides access to the the drawing status bar, the window the document is opened in, the Editor and TransactionManager objects. The Editor object provides access to functions used to obtain input from the user in the form of a point or an entered string or numeric value. For more information on requesting input from the user, see Prompt for User Input.
Document对象连同Database对象一起，提供了对图形状态栏、图形窗口、编辑器（Editor）及事务管理（TransactionManager）对象的访问。Editor对象提供了获取用户输入的功能，用户输入的形式如一个点、一个键入的字串或数值等。更多的请求用户输入的信息，见用户输入提示。
The Transaction Manager object is used to access multiple database objects under a single operation known as a transaction. Transactions can be nested, and when you are done with a transaction you can commit or abort the changes made. For more information on transactions and the Transaction Manager object, see Use Transactions with the Transaction Manager.
事务管理对象用来在被称为事务（transaction）的单一操作中管理多个数据库对象。事务可被嵌套，当与事务打交道时，你可以提交或终止所做的改变。更多的关于事务和事务管理的信息，请参见事务和事务管理。