Information Systems and Processes

XBRL Formulae in a Nutshell

Víctor Morilla

VIII European Banking Supervisors XBRL Workshop

Amsterdam

November 2007

2INFORMATION SYSTEMS AND PROCESSES

Introduction

XBRL 2.1 provides different types of validation for instance documents:

–Basic XBRL validation–XML Schema validation–Calculation linkbase–XBRL Dimensions

These validations are not enough in most cases:–Basic arithmetic operations: product, division, …–Arithmetic comparisons: item A must be equal to item B, …–Checks for the presence of elements

Derivation of new facts from existing ones is not possibleXBRL Formulae is meant to fill the gap

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Why a XBRL Formulae specification?

Requirements–Declarative language–Intuitive–Maintainable

–Extensible–Reusing existing standards

Business oriented

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Brief history

June 2005: first public working draft of Formulae RequirementsNovember 2006: the Formulae WG is constituted with the following purpose:

–Documenting complex functional relationships between concepts at a definitional level–Deriving new XBRL facts from available XBRL information–Reporting messages describing the outcomes of formula execution–Reporting consistency of formulae with the available XBRL information

January 2007: first Formula PWD Specification publishedFebruary 2007: public survey on first PWDJuly 2007: second PWD adds

–Implicit filter–Dimensional filters

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Parts of the XBRL Formulae specification

FormulaeVariables

Concept filterEntity filterScenario/segment filterTuple filterPeriod filterUnit filterDimensions filter

Generic labelsGeneric referencesXBRL FunctionsXBRL Functions RegistryW3C XPath 2.0

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XBRL Formulae step by step

(x1, x2, x3, …, xn) y

y = (a + b) * cArithmetic expression

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XBRL Formulae expression language: XPath 2.0

W3C Recommendation (since January 2007)Already supported by several toolsXPath 2.0 is an expression language:

Arithmetic expressionsComparison expressionsLogical expressionsConditional expressions…

Defines a set of standard operators and functions:+, -, *, div, mod, =, !=, <, >, and, or, …fn:abs, fn:ceiling, fn:floor, fn:concat, fn:upper-case, ……

Can call external functionsProprietaryXBRL Functions Specification: a set of predefined accessor functionsXBRL Function Registry

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XBRL Formulae step by step

(x1, x2, x3, …, xn) y

y = (a + b) * c

a concept: CurrentAssets period: January 2005

entity: Dutch Bank

b concept: LongTermAssets period: January 2005

entity: Dutch Bank

c concept: RiskFactorperiod: January 2005entity: Dutch Bank

y concept: WeightedRiskAssetsperiod: January 2005entity: Dutch Bank

Variables and filters specification

Formula specification

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Variables and filters

A variable is defined by a set of conditions: filtersConcept filterEntity filterScenario/segment filterTuple filterPeriod filterUnit filterDimensions filterValue filter

A filter can be relative to another variableb: period(a) - 1

A variable can be defined as a sequencey = sum(a)

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XBRL Formulae step by step

(x1, x2, x3, …, xn) y

y = (a + b) * c

a concept: CurrentAssets period: January 2005

entity: Dutch Bank

b concept: LongTermAssets period: January 2005

entity: Dutch Bank

c concept: RiskFactorperiod: January 2005entity: Dutch Bank

y concept: WeightedRiskAssetsperiod: January 2005entity: Dutch Bank

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Example instance document

Entity Period CurrentAssets LongTermAssets

RiskFactor

Dutch Bank January 2005 100.000 € 500.000 € 0.25

March 2005 150.000 € 600.000 € 0.33

May 2005 200.000 € 700.000 € 0.35

ACME Corp January 2005 55.000 € 20.000 € 0.50

March 2005 60.000 € 25.000 € 0.55

May 2005 70.000 € 30.000 € 0.60

… … … … …

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Example formula evaluation

a (CurrentAssets) b (LongTermAssets) c (RiskFactor)Jan 2005 / Dutch Bank: 100.000€

Jan 2005 / Dutch Bank: 500.000€

Jan 2005 / Dutch Bank: 0.25

Jan 2005 / Dutch Bank: 100.000€

Jan 2005 / Dutch Bank: 500.000€

March 2005 / Dutch Bank: 0.33

Jan 2005 / Dutch Bank: 100.000€

Jan 2005 / Dutch Bank: 500.000€

May 2005 / Dutch Bank: 0.35

Jan 2005 / Dutch Bank: 100.000€

March 2005 / Dutch Bank: 600.000€

Jan 2005 / Dutch Bank: 0.25

Jan 2005 / Dutch Bank: 100.000€

March 2005 / Dutch Bank: 600.000€

March 2005 / Dutch Bank: 0.33

Jan 2005 / Dutch Bank: 100.000€

March 2005 / Dutch Bank: 600.000€

May 2005 / Dutch Bank: 0.35

Jan 2005 / Dutch Bank: 100.000€

May 2005 / Dutch Bank: 700.000€

Jan 2005 / Dutch Bank: 0.25

Jan 2005 / Dutch Bank: 100.000€

May 2005 / Dutch Bank: 700.000€

March 2005 / Dutch Bank: 0.33

Jan 2005 / Dutch Bank: 100.000€

May 2005 / Dutch Bank: 700.000€

May 2005 / Dutch Bank: 0.35

March 2005 / Dutch Bank: 150.000€

Jan 2005 / Dutch Bank: 500.000€

Jan 2005 / Dutch Bank: 0.25

March 2005 / Dutch Bank: 150.000€

Jan 2005 / Dutch Bank: 500.000€

March 2005 / Dutch Bank: 0.33

March 2005 / Dutch Bank: 150.000€

Jan 2005 / Dutch Bank: 500.000€

May 2005 / Dutch Bank: 0.35

… … …

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Variable implicit filter

Implicit filter discards unwanted combinationsAll not explicitly filtered aspects of variables in a formula must match

Period Entity a (CurrentAssets)

b (LongTermAssets)

c (RiskFactor)

Jan 2005 Dutch Bank 100.000 € 500.000 € 0.25

March 2005 Dutch Bank 150.000 € 600.000 € 0.33

May 2005 Dutch Bank 200.000 € 700.000 € 0.35

Jan 2005 Acme Corp 55.000 € 20.000 € 0.50

March 2005 Acme Corp 60.000 € 25.000 € 0.55

May 2005 Acme Corp 70.000 € 30.000 € 0.60

… … … … …

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Validations

The validation specification defines different kinds of validations:Assertions

CurrentAssets + LongTermAssets > 0Assets must be equal to Liabilities + Equities

Existence of factsTotalIncomes is reported

Formulae consistency checkThe calculated value of TotalAssets given the formulae:

TotalAssets = CurrentAssets + LongTermAssets

, must be consistent with the value reported in an instance document

To be included in the next working draft

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Others

Documentation of formulae:Generic labelsGeneric references

Future developmentsFormulae chainingTemplate documents

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Summary

Variables

Filters

Formulae

XP

ath

2.0

XPathStd Functions

XBRLFunctions

XBRLFunctionRegistry

Validation

Gen

eric

lab

els

an

d re

fere

nces

Other usagepatterns

Other specs

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Next steps

Release of the next public working draftDevelopment of the conformance suiteRelease of the first candidate recommendation

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How can I contribute?

-Use cases for the conformance suite:

-Taxonomy files-Input instance documents-Expected result

-Review of the specification-Transmit your interest in XBRL Formulae to your software vendors

Ask not what XBRL can do for youAsk what you can do for XBRL

Information Systems and Processes

THANKS FOR YOUR ATTENTIONVíctor Morilla