How Table Definitions Work

tablesONLINE/ISPF requires detailed information about the format of the tables on which it operates. For example, to display a field, tablesONLINE must know where the data is within a row, the names of the field(s), and whether to interpret the data as text characters, binary integers, dates, or other data types.

This table-defining information is maintained in two places: the Data Table and the View.

Data table characteristics, such as table organization, search method, and row size are stored in a Data Table, which is defined by editing the table-definition block of the Data Table.

Other table-defining information specifies row characteristics and is stored in the View. Rows are defined in tablesONLINE Views.

tablesONLINE sees tables in pairs, each consisting of a Data Table and a View that contains the data definitions. Each table accessed by tablesONLINE must have both a data component and a View component. The name of each Data Table has the format shown in Table 191.

Table 191. Data Table Format

Byte Position



Uppercase alpha character


Uppercase alpha or numeric character


Uppercase alpha or numeric character or #

tablesONLINE automatically generates the View name by changing a bit of the first byte of the Data Table name, resulting in a lowercase letter.

A Data Table may have more than one associated View. Similarly, a View may be associated with more than one Data Table. Each View defines a different perspective of the Data Table. To the user, each View appears as a separate table.

There are three categories of table-defining information: row layout, tablesONLINE system characteristics, and tableBASE table definition.