The National Hydro Network (NHN) product is acessible on the Open Government of Canada Portal (open.canada.ca/en). Each NHN dataset corresponds to a NHN Work Unit Limit which delimits the territory covered by the dataset. This limit makes up the territorial divisions from which are produced and distributed NHN datasets.

The NHN Index is a national index that groups together all “NHN Work Unit Limits” at a specific time “T” for the entire Canadian landmass. This index is updated and published at interval on the GeoBase portal according to a “per release” approach, synchronized with NHN data publication. Update and publication frequency is determined according to NHN data publication. The NHN Index was first published March 20, 2008. Because it is generated at a specific time “T” and comprises all “NHN Work Unit Limits in the country, those limits are thus at different editing stages, where some have been fully edited and others partially or not at all. Moreover, it is important to realize that “NHN Work Unit Limits” will be modified over time, for example when new more up-to-date source data become available.

The NHN Index is distributed in SHAPE (ESRITM) format. This document thus provides its description for this format. In particular, it describes file names, features and attributes that make up the index.

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