The field list

GDDM V3R2 Base Application Programming Reference

The field list

GDDM V3R2 Base Application Programming Reference
SC33-0868-02

The field list groups together all information about the layout of alphanumeric data on one GDDM page. New fields can be added to an existing GDDM page, or old ones deleted, by modifying the field list. To give additional flexibility, there may be more than one field list in any GDDM page, so that if an existing field list is used up, further field definitions can be added by creating a new one.

A field list consists of a header followed by field definitions.

The header contains:

The status of the field list
The number of field definitions in the list
The size of the field definitions
The cursor position on the page.

Each field definition contains:

The status of the field definition
The size and position of the field on the GDDM page
A reference to the field attribute bundle definition in the bundle list
A reference to the character data
Optional length of character data
Optional references to character attributes.

The field list is represented as a rectangular array of half-word integers, in which the first row is the header and the following rows contain field definitions.

It can be declared as a structure, or as a two-dimensional array stored in row-major order. Programming languages that use column-major ordering of two dimensional arrays will have to exchange rows and columns in the description which follows. Below is a sample PL/I declaration for a field list, where "depth" and "width" are the array dimensions used in the API call APDEF:


         DCL FIELD_LIST(depth,width) FIXED BIN(15);





                   Column (width)
                   1      2      3      4      5      6      7      8      9      10  ...
                   ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ 
     Row (depth) 1|List  |Used- |Used- |Cursor|Cursor|      |      |      |      |      |
                  |status|depth |width |row   |column|      |      |      |      |      |
                  |______|______|______|______|______|______|______|______|______|______|
                 2|Field |Field |Field |Field |Bundle|Char  |Actual|Color |Highlt|SS    |
                  |status|row   |column|width |row   |index |length|index |index |index |
                  |______|______|______|______|______|______|______|______|______|______|
                 3|Field |Field |Field |Field |Bundle|Char  |Actual|Color |Highlt|SS    |
                  |status|row   |column|width |row   |index |length|index |index |index |
                  |______|______|______|______|______|______|______|______|______|______|
                 ..      .      .      .      .      .      .      .      .      .      .
                 ..      .      .      .      .      .      .      .      .      .      .
                 ..      .      .      .      .      .      .      .      .      .      .
                  |______|______|______|______|______|______|______|______|______|______|



   Figure 23. Field list array

The numbers beside each component description below are the indexes of each item in the row. See Figure 23.

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