DATADICT.TXT - 5th of 19 digital documentation files distributed
               with the "Forest Fire Chronology of Saskatchewan"
               (FFCS) dataset.


<Document overview>

     Describes the data dictionary of the FFCS database.
     Illustrates the data flow within the FFCS dataset.  Provides
     field definitions of the spatial and attribute databases in
     the FFCS and lists valid entries.  Indicates utility of the
     redefined fields in the attribute databases.


<Spatial attribute tables for any given fire year>

     SK_F????.AAT (arc attribute tables)
          These database files are not related to any other
          databases.

     SK_F????.PAT (polygon attribute tables)
          These database files are related to other databases,
          (see the Data flow section).


<Attribute database linkage background>

     The key database associated with the coverages (SK_FIRES) is
     a master database.  Thus, a separate attribute file does not
     exist for every coverage.  Rather, all attributes for all
     fires are stored in composite databases.  The use of master
     databases simplified relating Polygon Attribute Table files
     to attribute databases.  Furthermore, quick summaries of all
     fires from all years can be made.  (Based on ESRIs
     recommendations as well as basic database theory, it is
     inadvisable to have very many attributes in the individual
     .PAT files).


<Databases related to the spatial attribute tables>

     The structures of the aspatial attribute FFCS databases
     follow.  Field definitions indicate the input width, output
     width and type.  All fields are either alphanumerical
     character strings (C) or integers (I).


     The SK_FIRES database (burn attributes)

          This database contains the names of fires, the area of
          the fire, as well as simple spatial summaries.  The
          fields in SK_FIRES are:

          Field          Definition     Example
          ----------------------------------------
          FIRE_NO        8, 8, C        '1990-002'
          FIRE_NAME      35, 35, C      'EASTSIDE'
          NR22_HECTARE   6, 6, I        10,000
          GIS_HECTARE    6, 6, I        12,964
          NTS250         15, 15, C      '74O/74J'

          Redefined fields:
          YEAR           4, 4, C        '1990'
          DIGNUMBER      3, 3, C        '002'
          GIS_SQKM       4, 4, I        129
          PRIMARY_NTS    3, 3, C        '74O'



<Data flow>

     The data flow is quite simple: the polygon attribute tables
     link via many-to-one or one-to-one relates to the SK_FFMB
     database.



<Description of all FFCS database fields, in alphabetical order>

     DIGNUMBER (arbitrary numerical fire label)

          A redefined field that contains the arbitrary fire
          number assigned during the burn digitization process.
          Can be used instead of FIRE_NO if data presented is
          only for one year and the year-prefix in FIRE_NO
          becomes redundant.  As the FIRE_NO field is always
          populated, so is the DIGNUMBER field.



     FIRE_NAME (the name assigned to a fire)

          Usually an arbitrary name assigned to a fire.  It may
          be tied to geographical characteristics ('Esker'),
          mapped names ('Round Lake', 'Wapiskau River'), the
          shape of the fire ('Football'), the start day or time
          of the fire ('Monday', 'Morning') or to any number of
          impulsive fire naming quirks ('Pizza', 'Trolley').

          Naming of fires that have merged involves a modified
          naming system in the database.  Usually (but not
          always), all fire names are provided, with the names
          separated by slashes.  E.g., the single boundary for
          the merged Ira and Isaac fires has a FIRE_NAME value of
          'IRA/ISAAC'.  Typically (but not always), the larger of
          the pre-merged fires is listed first.

          Many fires lack names and these fires have either a
          'UNKNOWN' or blank value in the FIRE_NAME field.



     FIRE_NO (fire identifier assigned during GIS operations)

          A completely arbitrary number assigned when the
          database was initially constructed.  The first four
          characters represent the fire year, and the last three
          represent the arbitrary fire number.

          There may be gaps in FIRE_NO values (e.g., may have a
          '1948-002' and a '1948-004' but might not have
          '1948-003').  These gaps are the result of removing
          fires from the database which: were primarily in
          agricultural land, or; were less than 1000 hectares in
          size, or; subsequent investigation revealed that the
          fire map quality was too questionable for inclusion in
          the database.

          Every fire has a FIRE_NO entry, no exceptions.



     GIS_HECTARE (area within a burn perimeter, hectares)

          Fire area totals derived from a UTM extended zone 13
          GIS coverage.  Note that this number does not
          necessarily equate to the number of hectares burned, as
          green islands within the burn are usually not accounted
          for.  Furthermore, mapped fire perimeters do not always
          depict the true perimeter.

          The GIS_HECTARE area totals are usually different than
          those in the NR22_HECTARE field.  Extended UTM zone
          area summation errors notwithstanding, the GIS provides
          area totals that are derived using a consistent
          methodology.

          The area totals for multi-polygon fires are summarized
          into a grand total.  The GIS_HECTARE area totals are
          truncated from the square meter area numbers used by
          the GIS.  They are not rounded.  The error associated
          with the truncation is trivial: many fire area totals
          cannot be considered accurate even to the nearest 10
          hectares, so rounding error to the nearest hectare is
          considered acceptable.

          Every fire has a GIS_HECTARE value, no exceptions.



     GIS_SQKM (area within a burn perimeter, square kilometers)

          A redefined field that truncates the GIS_HECTARE total
          into square kilometer format.  Being a redefined field
          of GIS_HECTARE, every fire has an associated GIS_SQKM
          entry, with no exceptions.




     NR22_HECTARE (estimated area burned)

          Contains the Forest Fire Management Branch estimate of
          the size of the fire.  As with the GIS_HECTARE field,
          these numbers do not necessarily indicate the number of
          hectares burned.

          The NR22_HECTARE estimate may have been provided by
          field staff or could have been calculated by FFMB in
          the office.  These values are therefore generated by a
          number of people using various measurement techniques.
          As such, these values clearly could not have been
          calculated consistently throughout the span of the FFCS
          or perhaps even within a single fire season.

          Not all fires have a NR22_HECTARE estimate.  This is
          particularly applicable for fires occurring in the
          1940s, 1950s and 1960s.  If a NR22_HECTARE value is
          unknown, then the field contains a value of zero.



     NTS250 (National Topographic Series reference)

          This field was inserted for database users who do not
          have a GIS, thereby providing a semi-spatial touch to
          an aspatial database.  The NTS250 field also allows for
          quick queries of fires within a NTS250 mapsheet of
          interest by using a "contained in" query.

          The format of the NTS250 field (e.g., '73G/73F') lists
          the mapsheets in which the fire occurred in order of
          relative proportions and NOT in alphabetical order.  In
          the example given, more land burned in 73G than in 73F.

          Every fire has at least one (and as many as four)
          NTS250 mapsheet names associated with it.



     PRIMARY_NTS (predominant NTS250 in a multi-NTS250 fire)

          A redefined field that indicates the NTS250 mapsheet
          which contains the highest proportion of the burned
          area.  Every fire has a PRIMARY_NTS entry associated
          with it.



     YEAR (the year that a fire occurred)

          A redefined field that is rather straightforward;
          indicates the year of the burn.  Being a redefined
          field of FIRE_NO, every fire has a YEAR value.



<Redefined fields>

     The INFO database format redefined fields are not
     necessarily ported across to other databases (for example,
     dBASE cannot handle the redefined fields).  Other techniques
     may have to be used to achieve redefine-like functionality
     in such database software packages.



<Associated documentation>

     DATAISSU.TXT


This document prepared by:

Ott Naelapea
Wildlife Branch
Saskatchewan Environment & Resource Management
Box 3003, 800 Central Avenue
Prince Albert, SK.  S6V 6G1
CANADA
(306)953-2671 - Tel.
(306)953-2750 - Fax.

November 28, 1996
