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GIS Guide to Good Practice |
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4.3 Combining and integrating attribute databases
4.3.1 Data standards
Successful database integration relies on the implementation of
data standards. These aim to facilitate the production of a common
frame of reference for archaeologists, endorsed by the profession
as a whole and implemented in a widely compatible national network
of databases and digital archives. Currently core data standards are being defined for many fields of archaeology, from portable
items such as MDA
Archaeological Object Thesaurus (MDA 1998)
and the International Guidelines for Museum Object Information, produced
by the International Committee for Documentation (CIDOC), to the
draft data standards for SMRs and revisions of the RCHME Thesauri
of Architectural Types, Monument Types, and Building Materials. Another
useful resource is MIDAS (RCHME 1998).
Outside of the profession, essential standards have been set for
such data sets as British postal addresses (BS7666), and international
naming conventions for countries (ISO3166). See Appendix 2 for a list of
appropriate data standards. The basic process involved in the integration of data from external
databases relies on compatible field structure. This means that
complementary fields in both the source and target databases must
be of a compatible type (Integer, Floating Point, Date, a Character
field of an appropriate length etc.) to avoid the loss of data
during the integration process. Some features of certain databases
(e.g. DBASE memo fields) are
difficult to export to other systems and may require specialist advice to avoid their loss. The new
data should be date stamped digitally by the computer operator
and a record kept of its source and ownership. Data can be extracted from documents and typed
manually into an existing database, or whole reports can be captured
speedily using a commercially available optical character scanning
suite. These convert scanned text into digital characters which
can be saved into a variety of word processor formats. The character
interpretation is never 100% effective and will require spell-checking
and proof-reading before it is used, but this method
can save a great deal of time, especially when capturing printed
table data. Most often, the integration of paper-records will
involve some form of manual input, often involving a number of
separate individuals over a considerable period of time. Here
the importance of adherence to existing standards and guidelines
cannot be over-stressed. Such a process often involves a great
number of decisions that directly affect the quality of the source
data sets, as often very descriptive information is broken down
into the discrete thematic field structure of the database. To
ensure that the resultant database is usable it is important to
record such decsisions and ensure that a degree of consistency
is adopted throughout the process. |
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