In DP4, maps are used to define how information is displayed and printed by your application. Maps are usually designed with the Map Editor, which you use to enter the display text and to define the positions of the fields. You define maps in the same way for displaying screens and windows, and for outputting forms to a printer.
Maps are stored independently from an application. If you change the text on a map, you do not need to recompile your application programs. Maps are organised in mapsets in tables in the base dictionary of the database.
All the screens used by DP4 are defined as maps, and these are held on the system database. You can look at and edit these maps in exactly the same way as the maps on your application database, though you need to be careful what you do.
Applications that build their user interface with DP4 maps gain all the benefits of the DP4 user interface.
On the screen, maps are displayed in layers. The most recently displayed maps overlay what is on the screen already:
Your application can have up to 50 maps to the screen at any one time (and there is no limit in 4.6xx versions of DP4). Maps can be positioned in in two ways:
Automatic (or free) positioning
With this method the user interface manager is allowed to select a position for the map, taking accounts of various hints passed with the API. This method allows the interface manager to make best use of the available space on the screen, (which may be variable especially on a Windows based system).
Attached positioning
You can display a map with reference to a field that is on the screen already. This is called the attach map method.