Practice Profile: Table Linkbase

Abstract

This Practice Profile document explains the key features available in the Table Linkbase Specification to create rendering formats for XBRL data and its benefits. It is primarily targeted towards audience seeking a basic understanding of the technical specification. This document is not intended to explain technical implementations of Table Linkbase Specification. The features explained here are based on Table Linkbase 1.0, Recommendation 18 March 2014.

This practice profile discusses Why Table Linkbase is required, What features it offers, Who can benefit from it and Where it can be applied.

Why (it is needed)

Often the structure of forms required to present or edit reported data in XBRL reports goes well beyond the presentation of values in a simple linear hierarchy. The XBRL Table Linkbase addresses this challenge by allowing taxonomy authors more flexibility in defining report presentations. Table Linkbase facilitates taxonomy authors to define the presentation of data in a format that is familiar to business users and non-technical stakeholders.

Use Cases

Table Linkbase allows the creation and editing of report templates that facilitate:

• Simple input of reported values when generating XBRL reports
• Rendering of the reported XBRL data for business users

WHAT (it offers)

Table Linkbase facilitates representation of data in a tabular structure. This section covers the features it offers to create business reporting formats/layouts.

Complex templates

Table Linkbase can capture complex business reporting templates. These templates are modeled independently of the dimensional modeling of the underlying data points, allowing the Table Linkbase to provide a representation of the template that is familiar to users, whilst retaining a logical and consistent modeling of the data. For example, Table 1 illustrates a reporting template in which “Investment” and “Credit” (presented in the rows) are broken down by “Counterparty Exposure” (“Government” and “Non-Government”) and type of exposure (“Funded” and “Non-Funded”). Additional information about “Provision” and “Sanction Limits” are also included in the template.

Table 1 - Investment and Credit Exposure

In the absence of the Table Linkbase, the presentation of complex templates such as the example above cannot be adequately captured using XBRL. For example, while XBRL dimensions enable allowable data points to be defined, they do not provide control over how the data points are arranged into a template. In particular, XBRL dimensions provides no mechanism for prescribing which dimensions appear on which axis (e.g. that the Investment/Credit dimension should appear on the row axis), and there is no way to capture the situation where different parts of a table axis are modeled using different dimensions, as is the case with the column axis in the above table.

The Table Linkbase gives taxonomy authors flexibility over how the XBRL dimensions that are used to model data points are arranged into templates for presentation in an XBRL report. The aspects that may be controlled by the Table Linkbase include not just XBRL dimensions but also other aspects such as concepts, unit, entity and period.

Re-use of existing relationships

Table Linkbase can make use of relationships defined elsewhere in the taxonomy to define parts of the templates. For example, a hierarchy of primary elements defined by presentation tree can be referenced and re-used by a Table Linkbase, instead of redefining the structure again. Similarly, dimensional domain-member relationships can also be re-used. This is particularly useful, as the rows and columns of a table will often mirror the presentation hierarchy or XBRL dimension members.

Open tables

There are scenarios in which the number of rows, columns or sheets in a template is not fixed, but is dependent on the data that is to be reported. To allow for this, Table Linkbase has the ability to define “Open Tables” that are not restricted to a fixed set of rows, columns or sheets.

Let us take an example of reporting scenario in which either number of records, or periods or currency is unknown and hence it has to be kept open for users. Using the flexibility of ‘Open Tables,’ the taxonomy authors can define open rows, open columns or open sheets for the unknown aspects.

Table 2 illustrates a reporting template which captures details of directors for the reporting entity.

Table 2 - Details of Director

Let’s assume that list of directors are modelled as typed dimension in the taxonomy. While creating Table Linkbase as per above template, number of rows which represent each director is not known hence cannot be predefined. Feature of ‘Open Tables’ is handy to address this scenario. Taxonomy authors would create open rows for typed dimension for list of directors.

At the time of rendering the XBRL report, the number of rows or columns or sheets rendered would be based on the number of aspect values found in the XBRL document. At the time of creation of the XBRL report, XBRL-enabled software applications would typically provide user interface components to allow users to add additional rows or columns or sheets to the templates as needed, thereby giving them greater flexibility. The use of ‘Open Tables’ is applicable to any XBRL aspect for which the full set of possible values is unknown.

Repeating templates

It is sometimes desirable to repeat a reporting template multiple times for different scenarios. Table Linkbase allows tables to have a third axis (the “z-axis”) which is to indicate that the table may be repeated. In some cases, the reporting scenarios for which the table may be repeated may not be known when the taxonomy is created. Taxonomy authors will define the template once, and specify the aspects for which it may be repeated. The preparer will see separate templates for each reporting scenario and rendering of templates would be based on the scenarios reported in the XBRL instance.

Let us take an example of a template that captures currency risk. Instead of defining a different template for each currency, the Table Linkbase provides the option of defining the template once and specifying the possible list of currencies on its “z-axis”. Preparers have to simply select a single template and choose the currencies for which they would like to report.

Template labels

The Table Linkbase allows taxonomy authors to define labels for the rows and the columns of a template; there is no compulsion to adopt the standard labels defined for concepts and dimensions in the taxonomy. Labels for concepts and dimensions are often long, due to the need to be unique across the whole taxonomy. Within a template, it is often desirable to use more terse labels that are meaningful in the context of where it appears within the template. The use of such labels can make templates much easier to understand. It should also be noted that Table Linkbase specification encourages use of existing labels of taxonomy and thus this feature may be used sparingly.

HOW (it benefits)

Table Linkbase facilitates representation of data in a tabular structure. This section covers how Table Linkbase benefits data definition, creation and consumption.

Figure 1: Table Linkbase Data Lifecycle

The features of Table Linkbase enable taxonomy authors to define reporting layouts/business templates. Filers can then use these templates, defined using Table Linkbase, to create XBRL reports. Analysts can consume XBRL data in a predefined format using Table Linkbase.

Report creation

All dimensions (such as primary concept, taxonomy defined dimensions, units, entity and period) for each reporting data point in the template can be defined in a Table Linkbase. This means that business users are only required to understand the cells as they are represented in the template and not the underlying XBRL data point definitions. Software tools can simplify and streamline the process to produce correct XBRL, leading to a reduction in errors when compiling and sharing XBRL reports.

Data consumption

XBRL applications can use the rendering features of Table Linkbase and need not develop customization to support viewing. XBRL data can be rendered using the Table Linkbase, allowing data analysts, auditors and other independent users to review/compare the data in the same layout that users entered the data, or at least understand their data if users did not use a form-based application to submit the data (i.e. as per the original business templates). This visualisation is available in addition to using the underlying dimensional model that can be used to develop business intelligence solutions.

WHERE (it is applied)

The initial development of Table Linkbase was driven by the needs of European banking and insurance regulators with a requirement for collecting complex, highly dimensional, fixed-form data. Table Linkbase is a natural fit for fixed-forms reporting environments, as it allows the collector of the data to prescribe a standardized presentation for the data to be collected. The application of Table Linkbase to principle-based financial reporting environments is yet to be seen. In such scenarios, the reporting format is typically defined by the preparer, and is not imposed by regulators. Table Linkbase may still may still have a role, perhaps alongside Inline XBRL, for presenting reports in a predefined layout.

Further Reading

• XBRL Table Linkbase Overview
• XBRL Table Linkbase Specification
• XBRL Dimensions 1.0