5.3 Data structures

The LRC archaeological data structure, originally built upon the structures developed in association with NYCC, has been expanded to reflect changes in computing power and record sources that could not originally be managed digitally. The design objective has always been to provide fully integrated access to as many aspects of the archaeological record as possible.

The database, now managed on a day-to-day basis using Microsoft Access, combines a number of flat data tables that are linked by a primary key, the KEY_ID, which combines a three-digit Site Number, a two-character Area Code, a five-digit Context Number and, optionally, a two-character individual object code. Digital plans and the digital Matrix Diagram are likewise linked to the database by embedded KEY _IDs in the same format.

The principal table, the Context Record, combines factual and interpretative data within a single record. An individual Context may relate to a single layer, deposit, feature, cut or positive structural feature, such as a wall, and may on occasion relate to an exceptional deposit, such as a group of pottery sherds within another context. Individual contexts can be combined or grouped within a Master Context, such as all the elements of a post-hole building; multiple Master Contexts may also be grouped under a Master Context. Master Context information is maintained within the same data table as the individual Contexts.

Since the 1980s all finds have been recorded individually and there is no distinction between 'small finds' or 'bulk finds'; this does not mean that every individual object is necessarily matched by an individual record. If, for example, multiple objects are recovered from a sieved sample then the material is recorded by category, with the number of items reflected in a Number_Of field. The decision to adopt an individual object record-based system was based upon the need to incorporate individual 3-D coordinates, and to enable detailed spatial analysis across entire assemblages. The finds data recorded in the Object Record are materials driven, and allow finds of all types to be documented within a single record structure; this makes assemblage analysis easier than using different tables for each class of artefact or ecofact.

To facilitate the production of plans based upon material culture or environmental evidence, an additional FromDraw field is incorporated into both the Context and Object Records. This data field defines the drawn component to which the record relates, as in most cases only the overall layers and cut or upstanding features are drawn and digitised; most of the finds are derived from layers filling features, which are not individually drawn in plan. Incorporating this link field allows digital drawings to be generated, reflecting analysis of the feature contents using simple SQL queries from the finds database.


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Last updated: Wed Nov 11 2009