Chapter 2-1: Data Dictionary Overview
Field Types
There are thirteen field types in the APPX data dictionary:
- Domain
Fields are fields that directly express the attributes defined in a domain while they define and occupy new physical space in a file. There are nine distinct domain-type fields: Alpha, Format, System, Text, Token, Date, Logic, Numeric, and Same As. Refer to the Domain Types section for additional information. You can choose to set up physical fields to exclusively reference domains, or you can set up individual field types directly.
- Alpha
Fields are comprised of numbers, letters, and special characters (-, #, or &, for example).
- Format
Fields are like alpha fields except that an edit mask is the primary characteristic.
- System
Fields, often referred to as audit fields, display data that is provided by the system.
- Text
Fields allow the user to enter blocks of text on the data entry screen.
- Token
Fields are like alpha fields except that they have specific values that are stored as corresponding numbers.
- Numeric
Fields are restricted to number, decimal (.), and sign (-) entries.
- Date
Fields contain dates and/or times, from a hundredth of a second through a century.
- Logic
Fields are fields with possible values of yes
or no
, or
to represent an unknown value.- Synonym
Fields provide alternative names for referencing existing APPX fields. They occupy no physical space in a file aside from the fields they reference.
- Substring
Fields represent discrete portions of longer alphanumeric fields. They occupy no physical space in a file aside from the fields they are a part of.
- Group header
Fields are used to group other fields by identifying the beginning and ending fields in a group of fields. The group can then be referenced by the name of the group header field. Group headers occupy no physical space in a file aside from the fields that comprise the group.
- Group trailer
Fields are optional placeholders to allow for terminating a group without referencing a physical field. They provide a streamlined method to allow for additions to the end of groups. Group trailers occupy no physical space in files.