Each dataItem part and elementary structure item has a diverse set of properties, whether assigned or by default. You also may assign properties to a structure item that has subordinate structure items, but those properties are ignored unless the description of the property says otherwise.
Item properties may be meaningful only in a particular context; for example, when an item interacts with a database table. The properties may have no effect in other contexts, however, as when an item presents data to the screen. The benefit of that lack of effect is that you can re-use the same part declarations. With some exceptions, EGL allows you to maintain values for every item property, in every item.
Most often, you re-use part declarations to create consistency in presentation or validation. You might want several on-screen fields to have the same color, for example, or to restrict input to the same range of numeric values.
With the exception of a series of item properties that are likely to be set only in a form, each item property is in one of these categories:
The field-presentation properties have no effect on the data that is returned to the program; they are solely for output.
Properties include color and highlight.
For details, see Field-presentation properties.
The formatting properties affect data at output or at both input and output. Properties include align, which determines how data is placed in a field.
Any formatting property can be specified on a data item.
For details, see Formatting properties.
Properties include value, which indicates the initial content of a field when you are working in Page Designer.
For details, see Page item properties.
For details, see SQL item properties.
Properties include range, which specifies a high and low value for numeric input.
Any formatting property can be specified on a data item.
For details, see Validation properties.
Other form-specific properties are described in Form part in EGL source format.
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