Chapter 2-1: Data Dictionary Overview
Physical versus Logical Categories
Each of the APPX field types can be classified as physical or logical. The distinction between the two reflects a field’s physical space requirements.
Table 2-1-1 outlines the properties of physical and logical fields. Each is discussed in more detail in the sections that follow. You can also refer to Chapter 2-4: Files and Fields, for more information.
| Fields | Assumes Attributes From | Defines New Physical Space |
|---|---|---|
| Physical Fields Domain-Type Fields Alpha Fields Format Fields System Fields Text Fields Token Fields Numeric Fields Date Fields Logic Fields Work Fields | Domain or Field Field Field Field Field Field Field Field Field Domain or Work Field | Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes |
| Logical Fields Substring Fields Synonym Fields Group Fields | Alphanumeric Field Any Field One or More contiguous Fields | No Subset of existing Field Redefinition of existing Field Redefinition of existing Field(s) |