What is a data dictionary?
Naming conventions
Map accuracy
Map projection
Spatial analysis
Basic Terminology
The underlying systems

What is a data dictionary?
A Data Dictionary contains metadata, which is a description of the content, quality and other characteristics of each layer in a GIS database so the user can understand the data they are using. Standard metadata format will encourage more consistent descriptions of data that will make data more useful to more users. The metadata format for this document is based on the Federal Geographic Data Committee (FGDC) standards as described in the Content Standards for Digital Geospatial metadata (CSDGM)


Naming conventions
All files are named with the DOS 8.3 convention, i.e. up to eight characters followed by a three-character extension. File names are as descriptive as possible given the 8.3 naming limitation. For example, the school district shapefile is named "schdist.shp".


Map accuracy
SmartMap layers have two levels of accuracy. Tax lot based layers, e.g. streets, zoning and parks have a positional accuracy of plus or minus ten feet. The data collection scale is 1'=100' to 1'=400'. Environmental layers, e.g. contours and soils are based on USGS 7 1/2 minute quadrangle sheets and have an accuracy of plus or minus 40 feet. The data collection scale is 1' =2,000'.


Map projection
All SmartMap data are in Oregon State Plane South Zone, North American Datum (NAD) 1983, in units of international feet unless stated.


Spatial analysis
NOTE: Care should be taken to avoid implying data accuracy by overlaying information of lower accuracy onto data of higher accuracy. For example, although the soil data can be mapped with the tax lot lines overlaid, existence or non-existence of a soil type within a tax lot cannot accurately be determined.


Basic Terminology
The section below lists some of the most common terms used in this manual, and provides a description of the meanings.

Database or Table - These terms are used synonymously to refer to pieces of information stored in a conventional flat file or relational database. Examples include Microsoft Access data files, dBase or FoxPro DBF files, and ORACLE or Sybase tables.

Shape Files - These are standard desktop GIS data files. They contain spatial information (lines, points, polygons) created for use with ArcView and other ESRI products (Environmental Systems Research Institute, Redland, CA).

DBF File - Standard desktop database files. A format originally created for dBase, however it is accessible from almost any PC or Macintosh-based program that deals with data (such as FoxPro, ArcView, FileMaker Pro, etc.).

Geocode - The process of spatially referencing conventional database information. For example, you can 'geocode' a mailing list and the end result might be a map with points showing the location of each address.

Theme - In its simplest form, you can think of this as a mapping layer. Themes can have certain data sources, such as colors, drawing orders, and symbols to represent the data. Some commonly used themes with SmartMap include Tax Lots, Soils, Streets, School Districts, County Zoning, and Flood Plains.

Database Fields and Records - If you visualize a database table as being like a spreadsheet, the columns are fields and the records are rows.

Selected Set - A set of records (rows) in a table that meet a certain criteria. For example, you might create a selected set of tax assessment records that have a site address on Maple Street. You can then perform tasks on the selected set (such as printing mailing labels, or making maps) rather than the entire table.

The underlying systems
Many users make use of SmartMap without knowing the underlying systems upon which the programs were developed. Indeed, it is usually not necessary for the user to know about the specific engines that are powering the application.