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HLU class page format

Class name

This section provides a brief overview about the class.


This section describes the class's header files, class name, class pointer, Fortran class function, superclass, and composite class.

Header file

C developers should include this file in applications that use this class.

Class name

This is the name of the class described in the current module. The class name can be used in a resource file to specify a default for all objects of that class.

Class pointer

This tag is used in C programs where a class identifier is needed. For example, the NhlCreate call requires a class pointer to identify the type of object to create.

Fortran class function

This is the Fortran external function name. This tag is also used in the Fortran NhlFCreate call to identify the type of object to create. This tag must be declared as "EXTERNAL" at the beginning of a Fortran program.


This identifies the class "above" the class in the class hierarchy chart. All resources defined in a superclass are available to the current class.

Composite class

This identifies the composite classes that help define the functionality of the current class. A subset of the resources defined in a composite class are available to the current class.

Class-defined types

This section lists the relevant C types for the current class. Note that for enumerated type definitions, the enumerator, an integer value, and a C comment are listed in the definition section. These values can be used in different functions for setting resources. For example, Resources that have an enumerated type can be set using the SetInteger function with the enumerated value or the integer value, or using the SetString function with the string value. Note that the set of characters that are enclosed in quotes in the C comment field is the string representation of the enumerated value. This string value can be used in the SetString function, and the string value is case insensitive.

For more information, see the discussion of enumerated types in the Resource types module.


This section lists the local, composite, and superclass resources for the class.

Local Resources

This section provides a table that lists the local resource names and their class, type, default value, and access method.

  • Name - This is the resource name that is used in resource files as well as function calls to control characteristics of an HLU object. Clicking on the resource name will link you to a complete description of the resource and its valid values.
  • Class - The class table entry specifies the name of the class that the resource belongs to. The class name can be used in resource files to set all the resources that belong to a particular class. For example, the text item resource, txFont, has a class name of "Font". This class name could be used in a resource file to set all resources in the Font class to a single type, such as helvetica.
        *.Font   helvetica
  • Type - The type lists the HLU type of the resource. The type entries are linked to their type definitions.
  • Default - The default column lists the default value for the resource.
  • Access - The access column of the table specifies how the resource can be accessed.
    • R - specifies that the resource can be used in a resource file.
    • C - specifies that the resource can be set at create time with the NhlCreate (C) or NhlFCreate (Fortran) calls.
    • S - specifies that the resource can be set programmatically using the NhlSetValues (C) or NhlFSetValues (Fortran) calls.
    • G - specifies that the resource can be read programmatically using the NhlGetValues (C) or NhlFGetValues (Fortran) calls.

Composite Resources

This section provides links to the classes that provide the composite resources. Also, descriptions of any special limitations the class places on the use of the composite class resources is included.

Superclass resources

This section provides links to the resources of each of the superclasses.


This section gives a detailed overview of how to use the class, and it explains the functionality that is available.

Support functions

This section lists the HLU functions that are defined for the class.


This section lists the current status of the class implementation.

See also

This section lists related topics.