5. THE PROGRAM MODULES

Each of the four modules will be discussed in detail regarding its purpose, the options available and the links with other modules of the software.

5.1 CLASSIFICATION

5.1.1 Purpose

The purpose of this module is to define a land cover class according to two main phases:

• An initial Dichotomous Phase, where the user derives the main land cover type. For this phase at each level a choice is made between two alternatives, hence the term dichotomous. After having determined the main land cover type, the user can proceed to the next Phase, but the user can also define a generic class using only this initial phase.
• A subsequent Modular-Hierarchical Phase, where a land cover class is defined by determining one classifier at a time. The classifiers available are tied to the main land cover type. In this Phase, the selection of one classifier at a high level may have consequences for the options available at lower levels. The system is constructed in such a way that choices no longer valid in connection with a chosen classifier at a higher level become inactive.

At any level within these Phases the user can ask for the land cover class and store its Boolean formula, numerical code and class name in the module called "Legend."

5.1.2 Dichotomous Phase

In the Dichotomous Phase the user can select the major land cover category to which the land cover belongs. There are two ways to proceed through the options, to either:

• start at the top of the key and determine at each level which option is valid by clicking the appropriate button; or
• identify immediately to which major land cover type the class will belong and by clicking directly on the button with the arrow immediately below the button with the major land cover type name.

Having determined the major land cover type (Figure 12), the Dichotomous Phase is completed and the user automatically enters the next phase. A pop-up screen will inform the user of the change of Phase.

If the level of information needed or available to determine a land cover class is very limited, the user can select the appropriate choice(s) in this phase and a land cover class will be defined. This class will consist of a Boolean formula, a standard name and numerical code. This class can be stored in the Legend Module (see Section 5.2). Classes thus defined are broad categories because of the limited number of classifiers used. For more detailed definition of classes the user should apply the classifiers of the Modular-Hierarchical Phase.

FIGURE 12.
The Dichotomous Phase with the classifier options Primarily Vegetated - Terrestrial - Natural and Semi-Natural Vegetation selected.

5.1.3 Modular-Hierarchical Phase

The Modular-Hierarchical Phase is a phase where the set of available classifiers is tailored to the major land cover type. This means that the type, amount and hierarchical arrangement of classifiers will differ from one major land cover type to an other.

In each module, however, three groups of classifiers and attributes are available and they are always presented in the same hierarchical order. Each type of classifier and attribute is also presented in a different colour on the video screen (Figure 13). A distinction is made between:

• pure land cover classifiers at the top levels of the module;
• environmental attributes at the intermediate levels; and
• specific technical or discipline-related attribute at the bottom level.

FIGURE 13.
Example of the classifiers and attributes of two major land cover types: Cultivated and Managed Terrestrial Areas (A11) and Natural and Semi-Natural Terrestrial Vegetation (A12).

Pure Land Cover Classifiers

The difference between these classifiers and the attributes is that the land cover classifiers are strictly hierarchically ordered. One cannot skip a classifier and go on to the next one unless this possibility is provided for by the program, as occurs with "Semi-Natural and Natural Vegetation" and "Cultivated Terrestrial Areas and Managed Lands". The user must proceed step-by-step in order to develop the structural-physiognomic concept (see Sections 2.3.4.1 and 2.3.4.2).

The classifiers are also ordered according to their mapability. The classifiers at a high level have a higher mapping accuracy than classifiers from lower levels, which means that they will contribute more to establishing clear and precise boundaries between different land cover classes than will lower-level classifiers. If a classifier cannot be determined, the user can stop.

Definition of the land cover class results in:

• a unique Boolean formula (a coded string of the classifiers used);
• a standard name (nomenclature); and
• a unique numerical code that may be useful in GIS applications.

Both the numerical code and nomenclature name can be used to automatically generate a Legend (see Section 5.2).

The user will start to identify any land cover class using the pure land cover classifiers. A minimum number of these classifiers need to be determined before the user is allowed to combine these classifiers with any of the attributes. If the minimum requirement for classifiers has been satisfied, the button for proceeding to the environmental attributes will be enabled, as well as the buttons to show the class and save it to the Legend.

The pure land cover classifiers are always presented in blocks in which the choices are mutually exclusive, i.e., the user can select only one option. Even where there are two different levels, a more general level and a more specific level, presented in two rows (e.g., in Life Form "Woody" above "Trees" and "Shrubs" in Figure 14) only one option can be selected. If the user clicks on the button "Woody" followed by clicking on "Trees", the button "Woody" will return to its original, inactive, position.

FIGURE 14.
Example of classifier options at different levels of detail (major land cover type A12 - classifier Life Form with a first general level and a second more detailed level).

There are also options that further modify a classifier option (Figure 15). These are called Modifiers and they immediately follow a classifier option (e.g., in Leaf Phenology for Forbs and Graminoids; "Mixed" above "Perennial" and "Annual;" or in Height for all Life Forms). Modifiers belonging to one classifier option are mutually exclusive. Only after selection of the classifier can a modifier be added. If the user clicks the button of a modifier without having clicked on the appropriate classifier first, a message will pop up to inform the user that the classifier should be selected first.

FIGURE 15.
Example of modifier that further defines a classifier option (major land cover class A12 - classifier Leaf Phenology with modifier options Mixed and Semi-Deciduous).

The use of these modifiers will generate (examples are shown in Figure 16):

• a separate Boolean Code (e.g., "Basic Classifier: A3A10B2C1" and "Modifier: B5")
• a distinct numerical code which follows the classifier code and is separated from it by a hyphen (e.g., 20007-13152); and
• a change to the standard name (e.g., Continuous Closed High Forest).

The more levels with their classifiers that are used, the more specific becomes the land cover class defined. Choices made at a high level may have implications for the availability of a certain classifier at a lower level. If certain options are no longer valid the buttons are disabled. In this way the user is guided through the program and invalid choices prevented.

FIGURE 16.
Examples of Show Class windows with a land cover class defined in the Natural and Semi-Natural Terrestrial Vegetation major land cover type.

Environmental Attributes

The environmental attributes are not hierarchically ordered and the user is free to add appropriate choices in any order. Use of these attributes further defines the environmental settings in which a land cover unit is found (Figure 17). The options within one environmental attribute are mutually exclusive. Use of attributes will result in:

• a separate string of codes in the Boolean formula (e.g., Basic Classifier: A3A10B2C1-L2L7, Modifier: B5);
• no alteration of the numerical code (e.g., 20007-13152 remains unchanged); and
• no change in the standard name, as these choices follow the standard name and each choice refers back to the attribute itself (e.g., Class Name: Continuous Closed High Forest; Major Landform: Sloping Land; Slopeclass: Rolling).

FIGURE 17.
Example of Show Class window with a land cover class with additional environmental attributes: Landform and
Climate.

Specific Technical Attribute

Use of the specific technical attribute will further define the land cover class using the related discipline (e.g., for vegetation, the method of how species were recorded can be specified; for cultivated areas, the crop type can be specified) (Figure 18). Again choices are mutually exclusive. Use of a specific technical attribute will result in:

• a separate code added to the string of codes of attributes in the Boolean formula (e.g., Basic Classifier: A3A10B2C1-L2L7T3, Modifier: B5);
• no alteration of the numerical code (e.g., 20007-13152 remains unchanged);
• no change in the standard name as the specific technical attribute choice follows the standard name and after any environmental attributes used (e.g., Class Name: Closed High Forest; Major Landform: Sloping Land; Slopeclass: Rolling; Floristic aspect: Dominant species (Height or cover or a combination of both)).

The user can go through the levels of the Modular-Hierarchical Phase of certain major land cover classes and build up as many classes as needed. These classes can be stored in the Legend Module, described in detail in the next Section.

FIGURE 18.
Example of the use of the Specific Technical Attribute Floristic Aspect.

5.2 LEGEND

5.2.1 Purpose

The main purpose of the Legend Module is to store the land cover classes identified in a hierarchical structure that groups the classes according to the main land cover type. Therefore the Legend usually contains only a subset of the Classification, that is those classes which are applicable in the area (to be) interpreted or mapped.

In addition to providing a hierarchical structure, the Legend also offers capabilities to display, edit and add user-defined attributes to a land cover class. It provides standard descriptions for the classes identified and the classifiers used, and all this information can be exported in various formats.

Because in the Legend the classification is applied to a specific area, Mixed Mapping Units can be formed. A Mixed Mapping Unit can comprise two or three classes from the same major land cover type, or two or three classes from different major land cover types. The order of the classes in a Mixed Mapping Unit reflects the dominance in the mapping unit (see also Section 2.5).

5.2.2 How To Create A Legend?

Land cover classes are defined in the Classification Module. A Legend is created by storing these land cover classes in the Legend. To store a class defined in the Classification Module, the "Write Class to Legend" button needs to be clicked on in the Actions Panel of the Classification Module (see Section 4.1), upon which a sub-menu is shown (Figure 19). This sub-menu questions the user whether the class is a "Single or Mixed Unit?" The following choices are available: either

• clicking on the Single option stores the class defined in the Legend and the user can define the next new land cover class; or
• clicking on the Mixed option makes the program keep the first class defined in memory and await definition of the second and/or third component of the Mixed Mapping Unit.
• If the second land cover class is the ultimate component of the Mixed Mapping Unit, the user should then click on End Mixed, but if there is a third component the user should click on 2nd Mixed.
• To define a third, and final, component of a Mixed Mapping Unit, the third land cover class needs to be defined, followed by clicking on End Mixed.
• To annul storage of a land cover class in the Legend the user can select Cancel, or, if the second or third component defined should not be written to Legend, the same button can be used. However, by annulling this component, the system still expects definition of the second and/or third elements.

The Help button gives further information on which option to select in case of writing a class to the Legend.

FIGURE 19.
From the Classification Module to Legend: window in which the user has to select whether or not the defined land cover class is part of a Mixed Unit.

In the current classification (and its derived Legend) a Mixed Unit is defined as a mapping unit where more than 25 percent of the dominant cover belongs to another land cover class. The dominant land cover class is always the first class mentioned (e.g., Closed Forest/Herbaceous Fields indicates a Mixed Mapping Unit of forest and fields where the forest is the class covering the bigger portion of terrain (more than 50 percent), while the agricultural fields cover at least 25 percent of the area, but less than 50 percent).

The Mixed Mapping Unit is then stored in the Legend. The user can continue to define other land cover classes or switch to any of the other program modules.

There are two ways to enter the Legend Module, either:

• directly from the Main Menu; or
• from the appropriate button of the Actions Panel in the Classification Module.

In the Main Menu there is a button which leads the user directly to the Legend Module. However, if no land cover classes have been defined in the Classification Module and subsequently stored in the Legend, the Legend will be empty.

From the Classification Module there is a special button to go direct to the main Legend menu, from where the various options can be chosen, as explained below.

5.2.3 Adding User-Defined Attributes

Land cover classes can be "cloned" in order to add some specific user-defined attributes to the standard land cover class selected. This allows the addition of more specific and user-oriented attributes while maintaining a standardized land cover class. The user may want to further define a classifier and/or attribute already used, or the user might want to add a new attribute. A standard set of options is provided (see Figure 20).

FIGURE 20.
Window with the options for definition of the Type of Clone in order to add a User-Defined Attribute.

In order to clone a standard land cover class and add a user-defined attribute, follow the steps below (an example is shown in Figure 21):

• Identify the land cover class to be cloned in the Identify class to be cloned box.
• Click on the button Select.
• A window opens with Type of Clone, in which one option needs to be selected, followed by clicking either OK to accept or Cancel if the operation needs to be cancelled. The option selected will add a figure between brackets to the coded string of classifiers of the class (e.g., 20007-13152(3)).
• The cloned land cover class is shown in the lower part of the screen.
• Type the attribute to be added in the User's Label box and a description in the Description box, if any.
• Press Apply.
• A pop-up message with Cloned legend successfully recorded will be displayed. Press OK.
• Press Close when no more classes need to be cloned in order to add user-defined attributes.

FIGURE 21.
Example of Legend User-Defined Attribute within a mixed class.

5.2.4 Display

In Display, the classes contained in the Legend will be displayed in a pre-defined hierarchical structure (Figure 22):

1. The land cover classes defined are grouped under the main land cover type they belong to, and according to the Structural Domain within one major land cover type (e.g., Natural and Semi-Natural Terrestrial Vegetation with the structural domains Forest, Woodland, Thicket, Shrubland, Grasslands and Lichens/Mosses.) (Box 2 and Appendix B).
2. Within one domain, classes are hierarchically ordered according to the level of classifiers used.
3. Three items are displayed vertically in the same column: (1) the numerical code, the Map Code, of the land cover class; (2) the string of classifiers used; and (3) the Land Cover Class name.
4. The column User's Label will be displayed as an empty column unless a label has been added by the user in the Legend - Edit function.

Mixed Mapping Units will be displayed under the Structural Domain Mixed Class under the major land cover type of the first, and therefore dominant, element of the class.

FIGURE 22.
Example of Legend Display.

5.2.5 Edit

In Edit, the classes comprising the Legend are displayed, placing the elements composing the class in different boxes.

The numerical code and standard name cannot be edited. These are standard elements of a class and are identical for anyone in the world using the system and defining the same class. These elements help the user to trace which class needs to be edited.

The User's Label and Description are the two boxes in which the user can enter user-defined labels and descriptions. These will be displayed in the Legend - Display once entered.

Two buttons are displayed at the bottom of the screen:

• Delete to delete a complete land cover class from the Legend; and
• Close, use of which stores the new User's Label(s) and/or Description(s) in the Legend and returns the user to the main Legend menu. The Legend - Display option can be used to check that the operation has been implemented satisfactorily.

5.2.6 Standard Description

The user is provided with a Standard Description for every class defined in the Classification Module and stored in the Legend. This description gives more insight into the classifiers used and the structure of the class than can be inferred from the standard name alone. User-defined attributes are not incorporated in the Standard Description; for an explanation of those, the Legend - Edit option should be used.

In the Standard Class Description, classes are hierarchically arranged according to the Structural Domains of each Major Land Cover Type (see Box 2), identical to the Legend Display, and the following information is shown:

• The major land cover type with its hierarchically ordered Structural Domains followed by the Land Cover Class Code (LCC Code) and Boolean formula or Map Code (LCC Formula).
• The standard land cover class name (LCC Label) followed by the user-defined label, if any (LCC User-defined label).
• The Standard Description (Standard Description) of the class followed by the User-defined description, if any. This description may be useful in reports accompanying maps in which the classes of the map are described in more detail.

The Standard Description can be printed by selecting Print from the toolbar at the top of the screen (Figure 23).

FIGURE 23.
Example of the Legend Standard Description.5.2.7 Classifiers Used

In the Display, Edit, Add User-Defined Attribute and Standard Description menu options, the Boolean Formula of the land cover class defined is displayed. The menu option Classifiers Used gives the user the possibility to interpret what these code strings mean, as it presents, under the headings of the major land cover types, the key to the codes used in the Legend (Figure 24).

This explanation will be useful in GIS/database queries where the user wants to re-select the data according to a certain classifier or a group of classifiers. Combining numerical codes and the Boolean formulae allows re-grouping according to user-defined queries.

5.2.8 Print

Clicking on this menu option will not invoke a new screen display but will send the created Legend to the printer. The output appears as described under Display (Section 5.2.3).

5.2.9 Save/Retrieve

This set of options allows the user to Save and Retrieve the legends created and is without exchange facility with other LCCS users. A legend stored in this way can only be retrieved by the same copy of the software application.

• To Save a Legend: click on Save and a window will open in which the user is asked to type the legend name in the appropriate box. No pathway needs to be entered.

FIGURE 24
Example of Legend Classifiers Used.

• To Retrieve a Legend: click on Retrieve and a window will open containing the names of the legends already saved. Click with the mouse on the correct name and click OK or Cancel.
• The option Delete will delete a stored legend.

5.2.10 Export/Import

Clicking on this menu option will invoke a new screen display offering with four choices. This set of options allows storage of legends in specified formats and allows exchange of legends with other LCCS users on different computer platforms.

• To Export a Legend: click on Export and select one of the four options displayed, namely:

  

• The text file will store the Legend as a .TXT file; the HTML file as an .HTM file; the spreadsheet option as an .XLS file; and the external Access database for re-import as an .MDB file.
• select Export to export the legend in the selected file format(s).
• a new window is opened in which the user can type the name and select the directory in
  which to store the legend.
  

  

• To Import a Legend: click on Import and specify whether it is a spreadsheet or an external database file and type the pathname and filename of the legend to be imported.

5.2.11 New Legend

This menu's options removes the existing Legend, which can be stored in the Output to window specifying the directory and name. The default name is TLegend.txt and a new Legend can be created as the user is so informed.

5.2.12 Close

This menu option will return the user to the where the user was previously. If the user was in the Classification Module before, new classes can be defined and written to the Legend.

5.3 FIELD DATA

5.3.1 Purpose

In this module, which will become available in version 2.0, the sample site is described and other relevant information can be stored. These data are automatically classified by being translated into the classifiers, modifiers and attributes of LCCS. The sample site can be described using a minimum dataset, a user-defined set or a full set of items. The minimum data set contains only those items needed to meet the requirement to be able to classify the entry according to the Classification System. If the user-defined or customized option is selected, the user needs to choose from the menu which items will be described. These settings can be saved in a file. It will depend on the objectives of a field survey as to which option will be chosen.

The Field Data Module is designed in such a way that the user does not need to be familiar with the classification concepts. Based on the information observed, the Module will check the various concepts in order to define, for instance, the layering in a vegetation type or the type of cover present.

5.4 TRANSLATOR

5.4.1 Purpose

Existing classifications and legends can be translated into the reference classification. By translating them into the Land Cover Classification System, this system acts as a reference base in which correlation between classifications and/or legends becomes possible.

The Translator Module offers the possibility to:

• translate classes of existing classifications and legends into LCCS;
• assess similarity of classes according to other classifications and legends using LCCS as a reference base;
• compare classes of translated classifications and legends and their attributes, using LCCS as a reference base, at the level of the individual classifiers used; and
• to compare two land cover classes of LCCS and their attributes (these may be two classes belonging to the same major land cover type or two classes belonging to two different land cover types), which may be useful when comparing a preliminary land cover class with a validated land cover class in field surveys.

FAO will coordinate input of translated classifications and legends for the time being. Major current classifications translated into the system will come as standard with the software application or will be provided at a later date.

From the Main Menu the user can go directly to the Field Data Module. This provides a short cut in the event that preliminary classes need to be compared with final classes derived through field observation.

In the Menu, the user will also find an option to return to the Main Menu.

5.4.2 How to translate a classification or legend

Translation of external classifications and legends into LCCS can be done by using the Classification Module and thus creating a Legend (see Sections 5.1 and 5.2) which can be imported in the Translator Module, or by direct input of external classes. In both cases the Import option will be used.

Import

If the user has created a Legend containing all the classes of the classification or legend to be imported, these classes can be imported in the Translator Module one by one. In the menu of the Import screen (Figure 25), the option Retrieve From Legend should be selected, which displays the screen in which classes from the legend can be imported.

FIGURE 25.
First screen of Import.

The Retrieve From Legend option will open the Legend Export to Translator window. In the box the classes stored in the Legend Module are displayed. How to export a class from the Legend Module into the Translator Module is described below:

1. Identify the land cover class to be exported to the Translator Module (or Imported into the Translator Module).
2. Click on Select as 1st to display the class in the Classes Identified Frame.
3. Add the user-defined elements from the original external legend to the land cover class selected, i.e., add a numerical ID, type the original name in the box Class Name in Legend, type the external legend or classification name in the box Ext. Classification Name.
4. Select Export.
5. This will bring the user back to the Import window.
6. Select Process Class 1 to let the system find the corresponding information in the LCCS databases and type an ID in the box above GIS Code Class1.
7. Select Save Class to store the class.
8. Repeat for other classes.

If a class consists of two LCCS classes, i.e., a Mixed Class, the procedure is slightly different. The Select as 2nd option should be used immediately after having selected the first class of the mixed unit (Step 2 above). After having completed steps 3 to 6, the option Process Class 2 should be selected, followed by Steps 7 and 8. The components of a Mixed Class have to be defined as single classes in order to recompose the mixed class in the Translator - Import.

This stepwise procedure allows each individual land cover class in the Legend to be exported into the Translator Module.

The second option is to add the classes, one by one, into the Translator Module using the Import screen display and without using the Retrieve from Legend option (Figure 26). A new and unique legend name needs to be added to the existing list and for each class to be imported the user needs to follow the sequence below:

1. Type a unique ID in the ID box; this can be the code in the original external legend or classification.
2. Type a unique two-letter code to identify this legend or classification (e.g., AF is typed for the Afghanistan Land Cover Legend).
3. Type the original name in the Class Name in Legend box (e.g., Afghanistan).
4. Type Background Information in the appropriate box.
5. Type a unique sequential numerical ID for the land cover class in the ID box of the LCCS Translator.
6. Type the GIS Code Class 1 (derived from the Classification Module).
7. Type the codes of the Environmental Attributes (derived from the Classification Module), if any.
8. Select Process Class 1, the system will now find in the databases the corresponding class name.
9. Reiterate Steps 6 to 8 if there is a second component of the class, using the second set of boxes and click on Process Class 2 to finish.
10. Click on Save when the boxes are filled with the appropriate labels of LCCS.
11. Click on New Class to import a new land cover class.

This sequence needs to be completed for any class of the external legend to be imported. By clicking on Close the user returns to the Main Menu of the Translator Module.

FIGURE 26.
Retrieving individual land cover classes from the Legend Module into the Translator - Import facility.

Display Imported Legend

This screen will display the final result of the imported external classification and its translation into LCCS. The user can choose to display according to the order in the original classification or legend, or to display according to the order of LCCS. Mixed Classes will be displayed according to the dominant, and first mentioned, class.

To display an imported Legend, follow these steps:

1. Select the classification and press the Go Next button (button with arrow pointing to the right).
2. The imported classes will be shown in the order of the original IDs on the left side of the screen.
3. The Show LCCS Legend will display the translation into LCCS classes.
4. There are two other options for displays which affect the order in which the classes are displayed: Original A-Z follows the order of the imported legend or classification, whereas LCCS A-Z follows the intrinsic LCCS order.
5. The User-defined Legend Option will write selected classes to a file.
6. The Close option will bring the user back to the Main Menu of the Translator Module.

5.4.3 Comparison of External Classes

Similarity Assessment

The similarity of individual external classes to other legends or classifications can be quantified. Select the option Similarity Assessment in the Main Menu. In the screen display the user has to select the reference class with which the other classes will be compared. A number of threshold settings are provided. These values are stored in a table of correspondence in which the following assumptions have been made (see Appendix D):

• the classifier Trees is the same whether coming from Natural or Semi-Natural Vegetation or from Cultivated Areas; and
• the classifier Herbaceous comprises Graminoids and Forbs, or Non-Graminoids, therefore the threshold has been set at 50 percent. The same applies to Woody.

To make a Similarity Assessment of two classes (an example is shown in Figure 27):

1. Select the Classification Name of the legend that should provide the Reference Class.
2. Select Classes and highlight the appropriate class.
3. Click the Reference Class set of arrows to get the selected class in the Reference Class box.
4. Click the Compare button.
5. Click on the Reference Class button and the class selected will be shown on the left side, together with its classifier and the options used.
6. Select Empty Report and press OK.
7. Select the legend or classification to be compared.
8. Set the threshold values. Two groups are distinguished: (1) to set if the first classifier should be the same; (2) to set the threshold value of the similarity.
9. Click Process and the assessment will start. A pop-up message will be displayed when the assessment is completed.
10. Select Preview Report and a report will be shown showing the Reference Class, the legend or classification selected for similarity assessment and the results, namely the classes and the similarity value.
11. Select Close to return to the Main Menu of the Translator Module.

FIGURE 27.
First screen of the Similarity Assessment, in which the reference land cover class is selected and second screen in which a number of options need to be selected.

Comparison of External Classes

Once classes have been translated into LCCS, the system can act as a reference base for comparison. Individual classes can be compared at the level of their classifiers and attributes, though only those which are provided by the system; user-defined attributes will not be considered. By selecting the option Comparison of External Classes from the Main Menu, a screen will be displayed showing the translated classification available or legends and their class codes. By selecting a classification by clicking, and a class by clicking, the boxes with Class 1 and Class 2, if appropriate, will be filled. The arrows allow the user to select either of the two classes as the reference class. Selection of a second class of the same classification or legend, or a different one, followed by putting the selected class in the right box of class to be compared allows the user to go on to the next screen where the actual comparison will take place. Clicking on the button OK will bring the user to the comparison screen. Click on Display and it will show the two classes and their classifiers; clicking on the button Compare will activate the comparison. The comparison will take into account all the classifiers of the class to be compared with those of the reference class. The following colours may be displayed:

• blue: from the same classifier, the options selected are identical.
• red: from the same classifier, different options have been selected (e.g., from the classifier Life Form one class contains the option Trees and the other Non-Graminoids).
• Yellow: the classifiers are different and comparison does not make sense, or only one of the two classes contains this classifier.

The same procedure can be followed for comparison of Environmental Attributes, if any, by selecting the Env. Attributes option.

5.4.4 Comparison of two LCCS classes

Two classes of LCCS may be compared to one another at the level of the classifiers and attributes used. Such a comparison may be based on a class defined in a preliminary interpretation and the other one derived from field observation. By selecting Comparison of Two LCCS Classes from the Main Menu a screen is invoked in which the Class codes of the two classes to be compared should be typed, or the most recent data entry of the Field Data Module is displayed and the user has to fill the box with the class to be compared. The Reference Class and Class To Be Compared can also be entered manually by typing the correct codes in the appropriate boxes. The same set of screens will thereafter be displayed as described under Comparison of Two External Classes (Section 5.4.3). Figure 28 shows an example of two external classes being compared.

FIGURE 28.
Comparison of two external classes using LCCS as reference classification system.