Data Elements
A Data element is a unit of EDI data. For example, sender ID and receiver ID are data elements.
Each EDI standard contains a set of data elements specific to that standard. These data elements are stored in a data dictionary that provides the following information about each data element:
- Name of the element
- Description of the element
- Data type: numeric, alphanumeric, or date
- Minimum length of the element
- Maximum length of the element
- Element type: fixed-length or variable-length
Fixed-length data is a type of data element or segment with a specific number of characters. For example, a company name data element might have a fixed length of 35 characters.
Variable-length data is a type of data element or segment with no fixed number of characters. For example, a sender ID data element can be one to fifteen characters in length.
A Data element separator is placed before each data element in a segment to mark the beginning of that data element. Without data element separators, an EDI translator does not know where one variable-length data element ends and another begins.
Data element separators must be defined in the EDI data format. When defining a data element separator, select a character that is not likely to appear in the data. This will help prevent translation errors that might occur during processing. Common data element separators are the asterisk (*), used in the ANSI X12 standard, and the plus sign (+), used in the UN/EDIFACT and TRADACOMS standards.
An EDI standard specifies where a data element appears in a segment. If a data element contains information, the information is displayed between the data element separators. If a data element does not contain information, there is only a space between the data element separators. If the last data element in a segment does not contain information, nothing appears for that data element.
The following figure shows a data segment that has four data elements separated by asterisk (*) data element separators. However, there is no data for the third of the four data elements, which is shown by two consecutive asterisks.

Composite Data Elements
A composite data element is a data element made up of smaller units called sub-elements. A sub-element separator character, such as a colon (:), marks the beginning of the sub-element.
For example, ITEMNO is a data element in a purchase order. ITEMNO consists of three sub-elements, the part number, an aisle number, and a bin number. If part number 345 is located in aisle 9, bin location G, the data element ITEMNO output would be 345:9:G.
The following figure shows a composite data element with a colon (:) sub-element separator:
