XBRL Table Linkbase

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XBRL International has recently published a new specification: Link-TLB which enables the creation of tables in a DTS, or tables that allow input or display facts based on an instance.

This page offers background material to this specification and the SBR position in implementing it.

A TLB is created in a taxonomy as a (generic) linkbase. A TLB linkbase has an extended linkrole (ELR) which can contain one table, a resource. Every table can hold up to three axes (X, Y, Z), also resources. Each axis can be constructed from nodes. A single node has aspects which point to concepts or combinations of concepts in the taxonomy. A node can be a single primary or a set of dimension-member combinations as is normally used in the context by the segment/scenario container element. Nodes can be nested. By nesting the 'spanning' is revealed; how many columns or rows are utilized by the single node (not applicable for Z-axes). Every node can be equipped with (generic) labels to optimize presentation.

An alternative to using nodes is referring to relationships by including the ELR and the 'start' parent in the ELR. Software will now resolve all relationship children and assign a column or row to them. All relationships are allowed to be used in this way, but it is obvious that a parent-child (presentation) relationship is meant. This structure cannot be used for Z-axes.

Software is expected to be able to distinguish between cells that can hold valid fact values and which cannot (by evaluating the dimensional space tied to each cell by the intersection of all axes nodes). Software is also expected to be able to render a Z-axis upon a table. In MS-Excel tabs are being used but the specification is not prescribing any method (a pick-list of Z-axis values would also be acceptable).
By NOT specifying any nodes to either X or Y, the user may want to indicate a single axis table. The specification prohibits this. Both X and Y MUST be present. By specifying only a primary or a typed dimension for the 'unwanted' axis, software will interpret this as a single axis table and will allow the reporter to add rows or columns whilst reporting facts.

No TLB creation software is available. Software is able to render tables and use them as input GUI.

Advantages

  • Finally a specification that allows representation of the dimensional model in a taxonomy to be used on paper or monitor.


Disadvantages

  • TLB does not support tuples. Because of timing issues tuples have been dropped in the development. Tuples are still on the menu for a future version.
  • TLB is not supported by versioning.
  • Formulae cannot express their error messages in the form of cells of a table.
  • The optional TLB specific labels on rows and columns introduce the possibility that these labels express a completely different view than the (dimensional) aspects that used to form the axes.
  • Use of formulae filters to create the axes makes this specification difficult to manually create tables.


SBR utilisation
As long as tuples are not supported, SBR cannot use this specification.