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Appendix 2: The CSA layer-naming convention

Harrison Eiteljorg II, Kate Fernie, Jeremy Huggett and Damian Robinson, with additional contribution by Bernard Thomason. Revised by Stephen Dobson, Ruggero Lancia and Kieron Niven (2011), Archaeology Data Service / Digital Antiquity, Guides to Good Practice

The CSA layer-naming convention is based on layer names designed to specify the contents of each layer clearly. These make it possible to search for layers or groups of layers using the standard ‘wild card’ database searches permitting quick and efficient access to layers without having to remember individual names.

Each letter in the layer name designates information according to its position as well as the letter itself. The scheme permits the use of letters of the alphabet and the numerals 1 to 9 (not 0) for each position in the name. The dash/minus sign and the numerals 0 to 9 inclusive may be used for the dates.

Layer names from a model of the Acropolis entrance
Figure i: Two examples of layer names from a model of the Acropolis entrance

Coding the description

The eight characters used to describe what has been drawn on a layer are:

  • 1 – Indicates the kind of drawing layer, e.g. icons, 3-D model of artefacts, cracks, database links, dimensions, holes in a surface, labels, 3-D modelled surfaces, notes, 2-D plan, solid models, texture.
  • 2 – Indicates whether the feature/object was found in situ, had been disturbed, was a random find, was found in situ but moved from its last point of use, is hypothetical or is a natural feature etc.
  • 3 – Designates the general type of the area, e.g. public, domestic, military, work/manufacturing area, agricultural etc.
  • 4 – Designates the specific part of an area (dependent on character 3), e.g. hall, anteroom, meeting place, kiln, etc.
  • 5 – Indicates the general nature of the feature, e.g. buttress, column, pillar/post, gate, monument, pavement/floor, roof, stair, entablature, wall, etc.
  • 6 – Indicates specific nature of the feature (dependent on character 5), e.g. base, capital, mosaic, etc.
  • 7 – Indicates general material, e.g. animal fibre, building stone, concrete, bone, unbaked clay, metal, plant fibre, rough stone, worked stone, terracotta, mudbrick, wood, bedrock, etc.
  • 8 – Indicates the specific material (dependent on character 7), e.g. oak, obsidian, wool.

Coding the Dates

For each layer there are two dates, one defining the earliest date attached to material placed on the layer and one defining the latest date. There are ten characters for dates, five for a starting date and five for an ending date and unused spaces are filled with leading zeroes. BC dates include a minus sign in the first position. AD dates have an extra leading zero. This system only permits dates as far back as 9999 BC using the minus sign, but it could be adapted for earlier dates.

Dates are ’rounded’ to enable searching, thus a date in the first quarter of the 5th century BC is included in the layer name -0499 (start date) -0475 (end date).


Some material may exist on more than one layer; for example a triglyph found re-used in a secondary context could be modelled and positioned on one layer identified by its find spot and on another layer identified by the date and structure from which it is thought to have come.

The CSA layer-naming scheme described is an analytic scheme which may work less well for excavations in progress. Too much knowledge is presupposed by the system and different schemes may be used by excavators, e.g. separating material according to excavator, season, trench, etc.

A full explanation of the CSA layer-naming system (revised 2009) is available online at the Center for the Study of Architecture website[1]. The document provides both a general explanation of the way naming layers can enhance any project and a more specific set of suggestions.