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Help & guidance Guides to Good Practice

File types

Peter Brewer (Laboratory of Tree-Ring ResearchUniversity of Arizona, USA), Esther Jansma (Cultural Heritage Agency and Utrecht University, The Netherlands), Version 1.1 – June 2016, Archaeology Data Service / Digital Antiquity, Guides to Good Practice

(whilst creating, working with, and processing data)

There are currently approximately 24 different dendrochronological data formats in use within the dendrochronological community. While most are adequate for creating and analysing dendrochronological ring-width series, many of these formats are read by just one or two programs making them unsuitable for archival or data sharing.

Probably the most commonly used format worldwide is the Tucson decadal format which has been used since the late 1970s. It’s a relatively simple ASCII-based format based upon the structure of the punch cards it replaced. Whilst very common in laboratories around the world, the format has a number of limitations, not least the fact it has almost no capacity to store associated metadata. Limitations with regards the storage of metadata within the format, and the lack of a formal standardisation procedure have meant that a variety of ad hoc methods have been introduced by users and software developers over the decades. These result in digital ambiguities and incompatibilities.

Other popular formats, especially in Europe, are Heidelberg and CATRAS. The CATRAS format was designed for the program of the same name (Aniol, 1983, 1987), while the Heidelberg format was developed for use with TSAP (Rinn 2005). Both formats have some support in some other dendrochronological applications, but this support varies, especially with regards their less popular features. The CATRAS format is an undocumented proprietary binary format and as such we strongly recommend against using it for archiving or data sharing. In comparison, Heidelberg files are plain-text and the format is relatively well documented. While still not ideal for archival purposes, Heidelberg files are suitable for short-term storage and sharing of data.

The Tree Ring Data Standard (TRiDaS) was introduced in 2010 as a universal format for describing any sort of tree-ring data or metadata. We strongly recommend using the TRiDaS format for the long-term storage of dendrochronological data and metadata. One major obstacle to the universal adoption of TRiDaS is the availability of applications and utilities for processing and working with TRiDaS format data. At the time of writing this guide, the only application suitable for day-to-day collection, analysis and management of native TRiDaS data is Tellervo (Brewer, 2014; Brewer et al 2010). A number of applications routinely used within the dendrochronological community have their roots back in the 1980s (e.g. COFECHA and DPL). While these products are venerable, they still perform well and therefore until improvements or replacements can be made available, dendrochronological workflows must adapt to their limitations. With this in mind the universal dendrochronological data conversion tool – TRiCYCLE – was developed soon after the release of the tree ring data standard (Brewer et al. 2011). See Archiving file types for further information.