positional system at the county or local level, this may not be practical at the state government level. For example, in the case of the State of Ohio, NAD 27 is the basic reference system for horizontal data for a large amount of the existing spatial data for the state. Some states mandate the use of the SPC. Another major difference is theme related: The location of wetlands, ecosystems, land cover, watersheds, and geologic formations are themes a large number of state agencies use. In some cases historic buildings, monuments, or burial grounds are state themes as well as features required for disaster preparedness and emergency response.

It is evident that a state or tribal extended Framework must be defined with the cooperation of state or tribal officials, and that only those additional themes used for most of the state or tribal agencies should be incorporated into an extended Framework. A meeting of the major stakeholders concerned with geographic data layers at the state and tribal level needs to be convened in order to discuss and define an extended Framework. As in the case of counties, the outcome of this step must be a list of themes and their content.

The FGDC understands that it must develop effective coalitions with state and local government organizations if it is going to succeed in the development of an extended Framework. The committee is especially encouraged by the efforts to establish a strong working relationship with the National States Geographic Information Council (NSGIC), and considers that this is the primary partnership needed to undertake the definition of the extended SSDI.

SUMMARY OF SPATIAL DATA THEMES

Many data themes have been mentioned in the above short discussions. The responsibility of the different levels of government for the various themes are described in Table 1. Where the federal government bears primary responsibility, the supplemental collection at the state and local government level must at least meet the federal data standards. In most instances, state and local standards are more rigorous than those at the federal level. But where the primary responsibility resides with the local government, supplemental



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