ENABLE Reference Manual
 ENABLE ATTRIBUTES
 TREE Attribute
 • The level for the box at the first level of the tree structure
 must be lower in value than any other level that appears in
 the tree structure.
 • When you define a level for the box at the first level of
 the tree, do not include the LINK OPTIONAL.
 • When you define level numbers for boxes at subsequent levels
 of the tree structure, these level numbers must be higher in
 value than any box defined at a lower level in the tree
 structure.
 • You must include LINK OPTIONAL when you define the level of
 a box at any but the first level of the tree structure.
 • When you use LINK OPTIONAL, you must identify the parent box
 before you identify the child box. To do this, you can use
 either of the following forms of LINK OPTIONAL:
 LINK parent-join-field TO OPTIONAL child-join-field
 LINK parent-box TO OPTIONAL child-box VIA join-field
 Use the second form of this option only when the join fields of
 both boxes have the same field name.
 Examples
 The following examples describe values of the TREE attribute
 that build several different tree structures.
 Example of the TREE Attribute With Two Boxes. Building a tree
 structure for two boxes is a fairly simple procedure. You must,
 of course, identify appropriate join fields for each box and
 decide which box is to be the parent box and which box is to be
 the child. The box that you choose for the parent should be at
 the first level of the tree structure.
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