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Specialist Task Force 492:
TDL Phase 3: A Reference impementation

Who we are:


Team leader:
  • Philip Makedonski, 
Team Members:
  • Gusztav Adamis
  • Martti Käärik
  • Finn Kristoffersen
  • Xavier Zeitoun

What we do

TC MTS laid the foundation of the Test Description Language (TDL) with STF 454 in 2013 in terms of the basic concepts and their semantics. STF 476 built upon the work of STF 454, by adding the necessary language functionality to integrate TDL test descriptions into test automation frameworks and elaborating a standardised concrete graphical syntax for end-users and a TDL exchange format to be used by tools to foster tool interoperability. STF 476 also delivered an extension to TDL to enable refined structured test objective specification.

STF 492 is continuing the efforts on TDL at ETSI by developing an open reference implementation as a common platform to accelerate the adoption of TDL and lower the barrier to entry for both end users and tool vendors.

For more details, see our Terms of Reference

Why we do it

TDL bridges the gap between declarative test purpose specifications (what shall be tested?) and imperative test case specifications (how shall it be tested?) by offering a standardised language for the specification of test descriptions. TDL also contributes to the ongoing activities in MTS to establish model-based testing (MBT) technologies within ETSI.

It is expected that test descriptions in a standardised language will ease the development of executable tests as well as make test specifications easier to review by non-testing experts, thus improving the general productivity and quality of test development in industry as well as in the standardisation process by relieving test engineers from working on details of test implementations. An extension to TDL addresses structured test objective specification based on TPLan to bring test purpose specifications into the modelling world and streamline the test specification process even further, especially in the standardisation processes at ETSI.

The reference implementation developed by STF 492 is aiming to accelerate the adoption of TDL by lowering the barrier to entry for both users and tool vendors in getting started with using TDL. The reference implementation comprises graphical and textual editors, as well as validation facilities based on semantics refinements, and a UML profile for TDL to enable the application of TDL in UML-based working environments.

How we do it

The activities of the STF are coordinated on a regular basis with a dedicated steering group assembled by TC MTS to ensure that the work of the STF is aligned with expectations and requirements from the different stakeholders. The steering group is also supporting the work of the STF by providing technical guidance on key technical issues.

The STF will host a tutorial session on TDL at the UCAAT 2015 to showcase ongoing work on TDL and its reference implementation, as well as different application scenarios in a hands-on manner. During a dedicated session at UCAAT 2015, the public launch of TDL will be announced, including a keynote speech and statements from different stakeholders. For the duration of the UCAAT, a dedicated booth will provide information and demos related to TDL. Selected partners will also showcase their solutions related to TDL at the event. Further ongoing dissemination activities from STF members from research institutions include raising awareness and promoting TDL on their respective websites and within teaching and research activities. A dedicated project has been created on the online issue reporting portal for ETSI (ETSIs Bug Tracker) where change requests for TDL can be submitted and managed in an open and transparent manner.


The deliverables for the STF comprise an update to ES 203 119, as well as a new technical report on the reference implementation, encompassing:

ES 203 119-1 V1.3.1 - Part 1: An extension of the current TDL meta-model covering the design of new features to support automation of the generation of concrete (e.g. TTCN-3) tests;

ES 203 119-2 V1.2.1 - Part 2: The description of a graphical TDL default syntax that provides full coverage of the extended meta-model, i.e. it describes a concrete syntax for all elements of the meta-model;

ES 203 119-3 V1.2.1 - Part 3: The description of a TDL exchange format that represents a TDL specification in an unambiguous format used to exchange specifications between tools.

ES 203 119-4 V1.2.1 - Part 4: The description of an extension to TDL enabling the support for the specification of structured test objectives.

TR 203 119-REF V1.1.1 - Reference implementation documentation.

Time plan

The work of the STF is organised around three intermediate milestones, due for approval on July 2015, January 2016, and May 2016, respectively. The final drafts of the three deliverables will be submitted for approval to the 68th MTS plenary.

How to contact us

For further details, or if you wish to be involved in the work of the STF, please contact the STF Leader: Philip Makedonski at

This information is based upon STF working assumptions.

The views expressed do not necessarily represent the position of ETSI in this context.