1. A graphic pointer used with a mouse to point to a location on a terminal screen.
2. An internal pointer to a record in a table which provides a mechanism for processing a selected set of records.
The cursor is moved one by one through the set while operations such as display, query and update are
performed.
cycle
1. In pathfinding, a cycle is a path or tour beginning and ending at the same node.
2. In tracing, a cycle is a set of arcs forming a closed polygon. Upstream and downstream directionality are
undefinable in a cycle.
D
DAL
Data Access Language. Apple's former standard to allow applications to communicate with relational databases.
DAL is middleware on a network. It is a program installed on the database server to provide a common SQL
access for all database servers on a network. Apple has licensed this technology to Independence Technologies,
Inc.
dangle length
Minimum length allowed for dangling arcs during the CLEAN process. CLEAN removes dangling arcs that are
shorter than the dangle length.
dangling arc
An arc having the same polygon on both its left and right sides and having at least one node that does not connect
to any other arc. It often identifies where a polygon does not close properly (e.g., undershoot), where arcs don't
connect properly, or where an arc was digitized past its intersection with another arc (i.e., overshoot). A dangling
arc is not always an error. For example, dangling arcs can represent cul-de-sacs in street centerline maps. See also
dangling node.
dangling node
The endpoint of a dangling arc not connected to another arc.
data access security
Measures taken to control system users' ability to view or modify data. These measures can include logical views
of data and explicit access rights by group or individual users. See also access rights.
database
A logical collection of interrelated information, managed and stored as a unit, usually on some form of
mass-storage system such as magnetic tape or disk. A GIS database includes data about the spatial location and
shape of geographic features recorded as points, lines, areas, pixels, grid cells, or tins, as well as their attributes.
database design
The formal process of analyzing facts about the real world into a structured database model. Database design is
characterized by the following phases: requirement analysis, logical design and physical design.
DATABASE directory
The same as the Library Reference workspace. It is the system directory that LIBRARIAN uses to manage
information about a map library. Each map library has one database directory named DATABASE.
data conversion
The translation of data from one format to another. ARC/INFO supports data conversion from many geographic
data formats such as DLG, TIGER, DXF, and DEM.
data dictionary
A catalog of all data held in a database, or a list of items giving data names and structures. Also referred to as
DD/D for data dictionary/directory. Commercial RDBMSs have online data dictionaries stored in special tables
called system tables.