Large Instance Points16th Eurofiling Workshop Wednesday 12 December

Herm FischerMark V Systems Limited and Arelle open source XBRL processor

Study results•RAM consumption vs. instance size•Instance XML to DOM (XML only) 1 : 3 to 1 : 10•Instance XBRL to formula processor 1 : 60•Instance XBRL to SAX object model 1 : 15

•Conclusion•Constant-memory streaming approach suggested•Non-XML technologies eventually required

US SEC form “SD”•Mining and oil exploration “payout” details•Sample size:•Instance: 21.7 MB•Every filer uses extension taxonomy•150,006 facts•21,001 contexts•5 units•0 footnotes

Streaming XBRL in XML syntax•Base spec 2.1 working group note (WGN) & task force•Compatible organization of instance for streaming•SAX vs DOM improves speed, no XML persistence•Constant memory usage•Use for 2.1 & XDT validation•Challenges for•Financial validation (~GFM)•Formula processing•XPath (XML node access)

XBRL streamability issues•Order•Freedom to order facts, contexts, units, footnotes

•XML syntax detail•Formula & Table Xpath to nodes and XML structure

•Validation and formula strategies•Designed for complete instance in memory•Complex fallback and existence strategies

XBRL streaming approach•Constant memory•Backwards compatibility•Order constrained within instances•Contexts/units located as needed in instance

Financial Validation EFM/GFM•Full object models analysis in memory for•Context, unit, fact duplications (could use hashes)•Fact cross-dimension analysis (only some concepts)•History of concepts used•Roll ups, roll forwards, aggregations

•Full DTS model in memory for•Concept issues, label/definition issues•Missing / improper calculations, roll-ups, roll-fwds

•Can be re-architected for streaming environment

Global Ledger Architecture•Multiple content models required in parallel•Transactions•Company data•Account data

•Reformulate for independent streams or persistent company/account models.

Formula Response•Define subset of XPath for streamed processor•No node-axis features (“/” or “[“ operators)•More functions for context, typed dimensions, etc •Should allow use of non-XML implementations

•Define subset of formula processing•Consider SQL infrastructures•Consider OLAP features

•Reconsider use of features like•Fallbacks•Multiple instances of large data sets

Abstract Model Response•Abstract model is based on OMG MOF & CWM•Abstracted XBRL semantics from syntax•Implementation will layer on XML as well as•CWM (OLAP supportive technologies)

•Next step is a pilot project•Implement abstract model demonstration•Evolve and tweak specs•Provide prototype implementation