attribute: A numerical entry that reflects
a measurement or value for a feature. Attributes can be labels, categories,
or numbers; they can be dates, standardized values, or field or other measurements.
An item for which data are collected and organized. A column in a table or data
batch: Submission of a set of commands
to the computer from a file rather than directly from the user as an interactive
browse: A method of search involving
repeated examination of records until a suitable one is found.
choropleth map: A map that shows numerical
data (but not simply "counts") for a group of regions by (1) classifying
the data into classes and (2) shading each class on the map.
compute: Data management command that
uses the numerical values of one or more attributes to calculate the value of
a new attribute created by the command.
data definition language: The part of
the DBMS that allows the user to set up a new database, to specify how many
attributes there will be, what the types and lengths or numerical ranges of
each attribute will be, and how much editing the user is allowed to do.
data dictionary: A catalog of all the
attributes for a data set, along with all the constraints placed on the attribute
values during the data definition phase. Can include the range and type of values,
category lists, legal and missing values, and the legal width of the field.
data entry: The process of entering numbers
into a computer, usually attribute data. Although most data are entered by hand
or acquired through networks, from CD-ROMs, and so on, field data can come
from a GPS receiver, from data loggers, and even by typing at the keyboard.
data model: A logical means of organization of data for
use in an information system.
database: Any collection of data accessible
DBMS (database management system): Part
of a GIS, the set of tools that allows the manipulation and use of files containing
default: The value of a parameter or
a selection provided for the user by the GIS without user modification.
feature: A single entity that composes
part of a landscape.
flat file: A simple model for the organization
of numbers. The numbers are organized into a table, with values for variables
as entries, records as rows, and attributes as columns.
file: Data logically stored together
at one location on the storage mechanism of a computer.
find: A database management operation
intended to locate a single record or a set of records or features based on
the values of their attributes.
geographic search: A find operation in
a GIS that uses spatial properties as its basis.
hierarchical data model: An attribute
data model based on sets of fully enclosed subsets and many layers.
highlight: A way of indicating to the
GIS user a feature or element that is the successful result of a query.
identify: To find a spatial feature by
pointing to it interactively on the map with a pointing device such as a mouse.
join: To merge both records and attributes
for unrelated but overlapping databases.
key attribute: A unique identifier for
related records that can serve as a common thread throughout the files in a
locate: See identify.
macro: A command language interface
allowing a "program" to be written, edited, and then submitted to
the GIS user interface.
menu: A component of a user interface
that allows the user to make selections and choices from a preset list.
overlay: A GIS operation in which layers
with a common, registered map base are joined on the basis of their occupation
parameter: A number, value, text string,
or other value required as the consequence of submitting a command to the GIS.
query: A question, especially if asked
of a database by a user via a database management system or GIS.
query language: The part of a DBMS that
allows the user to submit queries to a database.
relate: A DBMS operation that merges
databases through their key attributes to restructure them according to a users
query rather than as they are stored physically.
relational model: A data model based
on multiple flat files for records, with dissimilar attribute structures, connected
by a common key attribute.
renumbering: Use of the DBMS to change
the ordering or ranges of attributes.
report generator: The part of a database
management system that can produce a listing of all the values of attributes
for all records in a database.
restrict: Part of the query language
of a DBMS that allows a subset of attributes to be selected out of the flat
retrieval: The ability of a database
management system or GIS to get back from computer memory records that were
stored there previously.
search: Any database query that results
in successful retrieval of records.
select: A DBMS command designed to extract
a subset of the records in a database.
sort: To place the records within an
attribute in sequence according to their value.
SQL (Structured Query Language): A standard
language interface to relational database management systems.
subsetting: Extracting a part of a data
update: Any replacement of all or part
of a data set with new or corrected data.
verification: A procedure for checking
the values of attributes for all records in a database against their correct