1 Introduction
The variable-scope specification define a relationship that allows explicit declaration of in-scope variables from another variable set, forming the basis for both tuple generation (see tuples specification) and a form of chained variable sets.
1.1 Background
This specification is a member of a suite of similar specifications that define specific types of criteria that can be used to select facts from one or more input XBRL instance. It enhances the fact selection capabilities of the XBRL Variables Specification [VARIABLES], and forms the basis for the tuple output production by the XBRL Formula Tuples Specification [FORMULATUPLES].
1.2 Relationship to other work
This specification depends upon the XBRL Specification [XBRL 2.1], and the XBRL Variables Specification [VARIABLES]. In the event of any conflicts between this specification and the specifications upon which it depends, this specification does not prevail.
1.3 Language independence
The official language of XBRL International's own work products is English and the preferred spelling convention is UK English.
1.4 Terminology
This specification is consistent with the definitions of any of the terms defined in specifications that it depends on.
1.5 Document conventions (non-normative)
Documentation conventions follow those set out in the XBRL Variables Specification [VARIABLES].
1.6 Namespaces and namespace prefixes
Namespace prefixes [XML NAMES] will be used
for elements and attributes in
the form ns:name where ns is the
namespace prefix and name is the local name.
Throughout this specification, the mappings
from namespace prefixes to actual namespaces is consistent
with
Table
1.
The prefix column in Table 1 is non normative. The namespace URI column is normative.
| Prefix | Namespace URI |
|---|---|
varsscope
|
http://xbrl.org/2010/variable/variables-scope
|
xbrlvarscopee
|
http://xbrl.org/2010/variable/variables-scope/error
|
eg
|
http://example.com/
|
fn
|
http://www.w3.org/2005/xpath-functions
|
link
|
http://www.xbrl.org/2003/linkbase
|
xbrli
|
http://www.xbrl.org/2003/instance
|
xfi
|
http://www.xbrl.org/2008/function/instance
|
xbrldi
|
http://xbrl.org/2006/xbrldi
|
xbrldt
|
http://xbrl.org/2005/xbrldt
|
xl
|
http://www.xbrl.org/2003/XLink
|
xlink
|
http://www.w3.org/1999/xlink
|
xs
|
http://www.w3.org/2001/XMLSchema
|
xsi
|
http://www.w3.org/2001/XMLSchema-instance
|
gen
|
http://xbrl.org/2008/generic
|
variable
|
http://xbrl.org/2008/variable
|
iso4217
|
http://www.xbrl.org/2003/iso4217
|
2 Syntax
This specification only provides a textual declaration of syntax constraints when those constraints are not expressed by the normative schema supplied with this specification.
Explanations of elements and attributes are only supplied when explanations are not already provided in other specifications.
Unless explicitly stated otherwise, a reference to a specific element MUST be read as a reference to that element or to any element in its substitution group.
2.1 Variables-scope relationships
An variables-scope relationship is a specific relationship between two variable sets and an expressed by an XLink arc.
This relationship makes the in-scope variables of the relationship's source variable set visible as in-scope variables of the relationship's target variable set.
Fact variables represent the same aspects in the target variable set as in the source aspect set, and participate in variable evaluation in the target variable set (e.g., implicit filtering).
If the source is
a formula, the optional
@name attribute allows associating an in-scope variable, with the
name specified by this attribute, to the fact node produced by the source formula.
The variable's value (if any) is the PSVI-validated result node.
If the result node is a tuple, the variable may be used, with the
location rule
to specify production of child facts within the tuple.
The variable has no aspects and does not participate in implicit filtering in chained variable sets.
[Herm Fischer: The in-scope variable for a formula's resulting fact node originally was specified to be a fact variable binding that had the usual fact variable aspects associated with it. However in developing formulas to test this it was impossible to work out reasonable implicit filtering in the chained variable sets (because there is no filter-control of these aspects). Hence the formula result in-scope variable is respecified to only provide a PSVI validated node and to serve as a reference for the location rule. ]
If the source is
a variableAssertion, the optional
@name attribute allows associating an in-scope variable with the
name specified by this attribute, to the test expression of the source assertion. The test expression result
is deemed a boolean atomic value.
This can implement a form of chaining, and also is used to provide visibility to the location aspect of a parent tuple, to implement output of child factVariables, for tuples production (see tuples specification).
Any of the variables made in-scope by this relationship may have the same variable name as a variable of the target variable-set, in which case the variable of the target variable-set is accessible, and the like-named variable of the source variable-set is not available in the target variable-set.
To declare an variables-scope relationship an XLink arc MUST:
-
have an
arcrole value
equal to
http://xbrl.org/arcrole/2010/variables-scope - have a variable-set resource as the starting resource of the arc
- have an variable-set resource as the ending resource of the arc
The arcrole value,
http://xbrl.org/arcrole/2010/variables-scope,
is declared in the normative schema.
variables-scope relationships MUST
be expressed by
<varsscope:variables-scope-arc>
as indicated by the restrictions imposed by the arcrole declaration
in the normative schema.
If either the source or the target of a variables-scope relationship is a formula with a formula-instance relationship to an instance that is not the standard output instance, then both the source and target must be formulas with formula-instance relationship to the same output instance. Error code xbrlvarscopee:differentInstances MUST be thrown otherwise. This is to allow a processor to complete processing of one formula instance at a time.
Error code xbrlvarscopee:conflictingAspectModels MUST be thrown if the aspect model of the source variable set differs from the aspect model of the target variable set.
2.2 Chaining by variables-scope relationships
Chaining by variables scope is a form of chaining, or staging in-scope variables and result items of one value assertion, formula, or consistency assertion, to be used as input terms by a subsequent formula, by explicit specification that the dependent variable set has in-scope access to the prior variable set's variables and produced formula fact.
| This example shows use of variables-scope to relate two formulas, one producing a = b + c and the second producing c = d + e, to each other, with this relationship. The c = d + e formula produces its output fact item in the standard output instance, and makes it available as a named result of in-scope variables, to be used by the dependant a = b + c formula. |
|
2.3 Chaining Processing Model
Processing order dependency is implied by variables-scope relationships where expression terms of a variable-set that is a target of a variables-scope relationship reference variables of the source variable set.
Recursion and iteration is not possible with this processing model and is detected because either would require a direct cycle in variables-scope relationships. (However limited steps of recursion could be simulated by providing different a formula resource for each such step of recursion, thus both avoiding a direct cycle and a possibility of endless looping.)