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XML Flattened The lessons to be learned from XBRL.

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Presentation on theme: "XML Flattened The lessons to be learned from XBRL."— Presentation transcript:

1 XML Flattened The lessons to be learned from XBRL

2 Presentation structure 1.XBRL and the domain it addresses. 2.The XML extensibility problem. 3.The XBRL solution. 4.Strengths and weaknesses of the solution.

3 What does XBRL do?  Primarily reporting rather than transactions.  Write once, read many.  A complex and changing problem domain.  Data reported in multiple dimensions at once.  A domain that is also highly regulated.

4 XBRL Architecture

5  Schema with minimal hierarchy.  Everything's global.  XBRL extensions to schema.  Linkbases define relationships between concepts and resources.  5 standard linkbases.

6 Why?  A counter-intuitive approach?  Doesn’t really use the tree structure that is characteristic of XML!  Requirements for flexibility:  eXtensible…  … but also semantically stable

7 The XML extensibility problem  Starting from a model that allows this:  How do we extend to allow this:

8 1: Generic Self-Describing Elements  Using dynamic typing in XML:  Poor schema validation.  Reliant on correct high-level analysis.

9 2: The XML schema approach  Using object orientation and substitution groups.  Allows us to use specific elements: greater semantic rigour.  Content model extensibility still problematic.  Defers the problem rather than solving it.

10 Hierarchies: why do we need them?  Hierarchies provide context: Joe Bloggs Jane Bloggs  Without context you have this (!):

11 Hierarchies: not always so important  Some hierarchies are about categorisation rather than grouping data.  Our example can be represented sensibly without a hierarchy:  Without hierarchies encoded in Schema, many of the extensibility problems disappear: concepts can be added and removed freely.

12 Hierarchies the XBRL way  Removing hierarchies like this still loses information.  XBRL replaces this information through linkbases.  Linkbases can express inter-concept relationships in a very “loosely coupled” way.  Also allows for an arbitrary number of “dimensions” to be superimposed on a single concept set.

13 Strengths and Weaknesses  In the remainder of the session we will look at strengths and weaknesses in 3 areas: 1.Extensibility. 2.Information reuse. 3.Validation.

14 XBRL Extensibility

15  XBRL is easy to override and extend.  Loosely-coupled networks of arcs.  Add new links and “prohibit” old ones  Modularised extensions - original remains unchanged.  XBRL framework itself designed for extensibility.  Add new types of arc, link, even whole linkbases.  “Segments” and “scenarios” provide another dimension for extensibility.

16 Extensibility - limitations  Complex webs of documents.  XBRL taxonomies are verbose:

17 Information reuse  Presentation neutral.  Instance contains raw, unstructured data – easy to reformat to whatever structure is necessary.  Modularised handling of internationalisation.  Semantic stability.  Meaning of concepts less likely to change over time.  Instance documents remain meaningful against new versions.

18 Information reuse - limitations  Less effective for some types of data structure.  Data with many nested structures may not be any more extensible than normal XML.  But XBRL still gives multi-dimensionality – c.f. XBRL GL  Requires specialist software.  Drawing in many documents at once makes processing complicated.  Possible to achieve some processing in XSL, but complicated, inflexible and fragile.

19 Validation  Modularised validation.  Different sorts of validation can be split up along many different axes.  Some new validation already proposed – formula linkbase.  Fine-grained validation.  Each validation rule applies to very precise concepts

20 Validation - limitations  Constrictions of linkbases.  Limitations of calculation linkbase.  Future development may use other structures for some purposes.  Overriding hard to control.  No concept of “finality” built-in.  But no significant technical barrier to constraining this more closely for particular applications.

21 Conclusions  An unusual modelling approach.  A tool to be used carefully.  Good for domains that can be modelled statically.  Potentially improves extensibility, validation & information reuse.


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