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Data and Information
Data Standards
101's and How Too's for creating a NPS-GIS Geospatial Data Standard
  • GUID

    GUID (pronounced gu-wid) is an ancronym of Globally Unique IDentifier . A GUID is a 128 bit number that can be expressed in string format and is a standard method in Windows and other operating systems of generating an identifier that is virtually guaranteed to be unique regardless of its source. GUID's allow distributed systems/users to generate their own identifiers with near certainty that they will not conflict with other identifiers created by others (i.e. a Globally unique ID's). The algorithm for generating GUIDs could generate 10 million GUIDs a second until the year 5770 AD and each would be unique.

  • Subtyping

    Subtyping is a concept in ArcGIS that allows a field (must be long integer) in a GeoDataBase feature class to be used to categorize data into separate feature "subtypes" without splitting data into multiple featureclasses. This is useful when features share the same attribute fields but may consist of conceptually different real world entities. One benifit of subtypes is that each subtype can have different value domains, default values, topology rules and split/merge edit behavior assigned. Not only does using subtypes organize the data into categories for display, but subtypes can be used to ensure consistency when new data is added or existing data is edited. The classic example of subtypes is to assign a road_class field to a Roads featureclass. The resulting subtypes would be the various road categories, each having different default values and domains for the attribute fields. For more information see: