Many screens are composed of multiple tables.
A screen can comprise multiple tables stacked from top layer to lower ones on the screen.
The upper tables on a screen are referred to as parent tables or ancestor tables. The top most table on a screen is referred to as master table.
Below master are referred to as detail tables or children tables.
A record in upper table associates with 0, 1, or many records in its immediate lower table by "linking" some fields of the two tables. This association enforces the following effects:
Only the upper record exists can the associated lower new ones be inserted.
If the upper records scroll, the associated lower ones scroll, too.
If an upper record is deleted, the associated lower ones are also deleted.
Refer to screen shots Figure 5-1.