PDF Forms & FDF - Create and use PDF & FDF forms, PDF XML Forms Architecture (XFA) Specification, FDF Reference, PDF Reference

XFA Specification

Chapter 3, Object Models in XFA

Scripting Object Model

106

…

</subform>

</template>

</xdp>

the expression

$.Sub_Total

resolves unambiguously to

$form.Receipt.Detail.Sub_Total

Scope-matching does not apply hence the expression does

not

resolve to the same-named field

$form.Receipt.Sub_Total

"$"

can also be used for expressions pointing to nodes that are higher up in the hierarchy than the script's

container. Use

"$.parent"

"$.parent.parent"

, and so on to climb levels in the tree. It is possible to

climb all the way to the root. The equivalent syntax for native ECMAScript expressions is

"this.parent"

"this.parent.parent"

, and so on.

Inferred Index

The previous sections have used as examples a template that is divided up into individual subforms for

each detail record. Conceptually such a template is arranged in a tree structure. However it is also possible

to create templates that are notionally arranged in a matrix, like a spreadsheet. For example:

</subform>

</template>

</xdp>

Instead of grouping the fields by subform, this static template simply repeats each of the

Description

Units

Unit_Price

, and

Total_Price

fields five times. Most likely these are arranged on the page as a

matrix four fields wide and five lines high, in imitation of a traditional pre-printed paper form.

SOM expressions provide a mechanism to deal conveniently with such arrangements. When

scope-matching, if an unqualified reference is made without specifying an index, the index of the