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THE CARTOGRAPHIC VORLD 
In 1978, the Lands Directorate of Environment Canada, Statistics Canada, 
Agriculture Canada and the Canada Centre for Remote Sensing established the 
Spatial Data Transfer Committee to develop a standard file transfer format 
for geocoded polygon data (Goodenough, et al., 1979). The resulting format 
vas designed to conform to "The CCT Family of Tape Formats" superstructure 
developed by LGSOWG for LANDSAT and other image type data. 
The design objective was to develop a standard format for the interchange of 
spatially encoded data in the form of polygon chains with the following 
properties: 
1. Machine and Language Independence. To achieve this goal, all fields 
are either ASCII or binary integer in type and multiples of four 
bytes in length. 
2. Expandability. The format was designed to be easily revisable. 
Extra space was reserved for the addition of information at a later 
date. The structure was designed in anticipation of revisions to 
the format and to accommodate spatial data transfer formats, 
including formats for line, point and raster data. 
3. Generality. The family of spatial data formats was designed to be 
sufficiently general to accommodate the variety of geographic 
information used by the participating agencies. 
4. Self-Definition. The files are self-defining with respect to 
spatial and descriptive data in the files. 
This format has been implemented and tested in several demonstration 
transfer projects (Goodenough et al., 1983; Korporal, 1983; Yan, 1982). 
In 1979, the Canadian Council on Surveys and Mapping formed three Committees 
to formulate National Standards for the Exchange of Digital Topographic Data 
(CCSM, 1984). In the Committees' second draft report, a data exchange 
format was described which conformed to the LGSOWG CCT Family Superstructure 
concept. However, it was found by the CCSM Committees that the format 
developed by the SDTC was not designed to handle the full range of data 
types typically used in topographic mapping (CCSM, 1985) and had to be 
expanded. 
In 1985, the CCSM began a serious review and revision of its standard. This 
new standard must be flexible, simple and upgradable. It should focus on 
topographic data which can be represented on maps as point, line and area 
features, all of which may have attributes or text, and spatial 
relationships. A secondary priority is a general Digital Topographic 
Information Model (DTIM) expandable to include thematic data such as 
forestry, geology, cadastral, land use, etc. with locational and attribute 
components and spatial relationships. At this time, it is not to deal vith 
image, grid or raster data nor with cartographic representation or 
symbolization aspects of topographic data. The standard deals with 
topographic and cultural phenomena on the surface of the earth normally 
represented by three coordinates (x, y and z). 
The guidelines provided by the CCSM Technical Subcommittee for a new 
standard were that it must meet the following criteria: 
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