ENABLE Reference Manual

ENABLE ATTRIBUTES
TREE Attribute
Since you connect the levels of the tree structure with links,
you must define the level of a parent box as being lower than
its corresponding child box. Depending on how you define the
links and levels within your tree structure, a box can be the
parent of several boxes at a higher level of the tree structure
and the child of a box in a lower level of the tree. Although a
box can be the parent of several other boxes, a box cannot be the
child of more than one box.
When you define the level at which a box resides in the tree
structure, ENABLE uses this information to generate the program
logic for the application. This logic indicates:
• For the box at the lowest level, the application can read or
insert any valid record.
• For boxes at all other levels, the application must read or
insert a record for the parent box (which must reside at a
lower level of the tree) before it can read or insert a
matching record for the child box.
In summary, the following rules apply to the levels of a tree
structure:
• Only one box can reside at the lowest or first level of the
tree.
• Boxes that are connected by a link cannot reside at the same
level of the tree structure.
• The level at which a parent box resides must be lower than
the level at which a child box resides.
• A box can be the parent of several boxes at higher levels of
the tree structure; however, a box cannot be the child of more
than one box at a lower level of the tree structure.
When you define the levels at which boxes reside in the tree
structure, these levels affect the appearance of the terminal
screen displayed by the application and also determine the
records that can be read or inserted for each box used by the
application.
Using the TREE Attribute. The following rules apply when you use
the TREE attribute:
• The name of the box at the first level of the tree structure
must appear before any other box names in the tree structure.
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