Sphinx a user-friendly assertion language

David NorthSenior Developer, CoreFilingEurofiling Workshop, Luxembourg, December 2013

What is Sphinx?• Domain-specific language for making

assertions about XBRL facts• High-level, semantic, based on an n-

dimensional world• Not XML• Designed for humans to write and

edit directly• Proprietary

History• 2009 – first prototypes• 2011 – stable language reaches 1.0• 2012 – version 2.0 incorporating real-

world feedback requiring breaking changes

• 2013 – (later abandoned) attempt to offer the Sphinx IP to XBRL International

The requirements Sphinx grew from• XBRL US (XUSI) – development of the

XBRL US Consistency Checks for quality/consistency of SEC filings

• CIMA – regulator needing to check quality/consistency of incoming instances

• Replaced a stopgap spreadsheet-based solution

Who uses it?• XUSI• CIMA• HMRC

Proprietary: Disadvantages• Not an XII standard• Fewer options for implementations• Difficult for a regulator to mandate

its usage by filers• Can't be part of DTS

Proprietary: Advantages• High quality tools available from

CoreFiling• Fast evolution of the language in

response to customer feedback

What can it be used for?• Rapid creation of business and

accounting rules• Typical checks might include:– X must be reported– Co-constraints (if X is reported, Y must

be too)– Comparing data across dimensions

The language• Based on item expressions• The most basic: [ ]• Represents the table of all items in

the instance. Operations on it apply to every cell in turn

• Restrict by axes (“aspects” in XBRL formula)– FooConcept[ ] – restriction to facts with

FooConcept– [Geography=UK, Product=Cheese] –

restricts dimensions

Lining up

How is the following expression evaluated?

Revenue[ ] = SalesRevenue[ ] + RentRevenue[ ]

ExamplesPlease refer to accompanying file “Sphinx Examples.txt”

Tools• Rules authored in SpiderMonkey,

potentially alongside taxonomy development– Can test against instances here

• Can plug authored “rulebase” into other CoreFiling tools both for GUI-based instance validation and command-line/web based validation (e.g. filter gateway).

Sphinx vs XBRL formula• Sphinx does lining up (implicit

filtering) by default• Sphinx cannot do fact creation• Sphinx cannot use XPath• User-defined Sphinx functions are in-

language only (no ability to make them implementation-defined)

Questions?