Extended Properties SQL Server

In using extended properties, you can add text, such as descriptive or instructional content, add input masks, and add formatting rules as properties of objects in a database or of the database itself. For example, you can add an extended property to a schema, a schema's view, or to a column in the view. Because extended properties are stored in the database, all applications reading the properties can evaluate the object in the same way. This helps enforce consistency in the way data is treated by all the programs in the system.

Extended properties can be used for the following:

Specifying a caption for a table, view, or column. Applications can then use the same caption in a user interface that displays information from that table, view, or column.
Specifying an input mask for a column so that applications can validate data before running a Transact-SQL statement. For example, the required format for a postal code or telephone number column can be specified in the extended property.
Specifying formatting rules for displaying the data in a column.
Recording a description of specific database objects that applications can display to users. For example, the descriptions may be used in a data dictionary application or report.
Specifying the size and window location at which a column should be displayed.

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