One of the problems arising while creating applications designed for an operation with an ENC, is the necessity of working with user-defined data. Format of such data is not known a-priori also it may be different for different users or may change with the lapse of time.

A possible solution is the creation of a final application allowing access to its internal functions and resources. This access is modified with a help of scripts - text files, containing executable code. If it's necessary, e.g. when reading data or displaying users objects, a script is being played by the application. For example, a user faces a new type of an object in his database which has to be displayed. This task is being solved in three steps. First, the object is being described in an object dictionary. Second, a new data loading script is being written or the present data loading script is being changed. And at last a new data presentation script is being written or the present data presentation script is being changed. In practice all above procedures could be expressed by a single text file, including the functions of object dictionary, data loading and data presentation. In this case the application is being remained unchanged, but due to such an approach its range can be considerably extended.

The "open interface" approach is based on the scripts interpreter that features:

• an interface or a functions set providing an ENC forming on the basis of user-defined data and displaying of this ENC on the  screen;

• compactness ensuring possibility of the interpreter use in any application oriented on a chart work.   

A scripts interpreter uses a specific dKart script language, oriented on a operation with the cartographic information. A syntax of this language is close to the one of C programming language.  

The dKart script language includes 2 groups of functions:

• the functions used for an operation with cartographic data of geo-referenced context;

• external functions that support operation with an operating system, access to databases, mathematical functions etc.

• work with an objects dictionary (creation, modification, etc.).

• work with cartographic objects (creation, modification and deletion, etc.).

• work with object attributes (creation, modification and deletion, etc.).

• work with objects of point, linear, area and 3D types of geometry (creation, modification, recognition and deletion, etc.).

• operation with a geo-referenced context, (creation, positioning, displaying, defining of visible region, querying, etc.)

• access to Windows GDI functions;

• databases operations;

• mathematical functions;

• string operations;

• files operations;

• auxiliary functions (data conversion, etc.).