contents.gifindex.gifprev1.gifnext1.gif

Dataset member definition files

The main purpose of these files is to give loaded data sets descriptive names rather than just filenames. These files also specify the type of spatial data or type of tabular file format, as well as provides a link to the associated attribute definition files. These files are stored in the sub-directories specified by the dataset definition file (<subdirectory name>.def). The files are named <dataset directory name>.def. The following shows the first four lines in the aari_dis.def file:

"Theme-ID","Themealias","FeatureClass","Aliasfile","CoordSys"

"AARI -> FNI data delivery 1996 - dataset definition table",,,,

"aari_dis","Discontinuities in ice - data points","Point","aari_dis.fld","dd"

"DiscontinuitiesInIce","Discontinuities in ice","Table","DiscontinuitiesInIce.fld","dbf"

The first line is common to all these files and must not be changed. The second line is a comment line identifying the data set. The four commas ending the line must be there. The third and fourth lines define two data set members. The first column ("Theme-ID") includes the storage names (ARC/INFO coverage name, ArcView shapefile basename, dBase file basename, etc.) of the data set members, e.g. aari_dis. The second column ("Themealias") specifies the theme alias name that will appear in the View's Table-of-Contents (TOC) or the document name (for a table) appearing in the Projects window. The third column ("Featureclass") specifies the type of spatial feature (point, line, polygon, or table), while the fourth column ("Aliasfile") specifies the name of the respective data set member attribute definition files. The featureclass specification is used to determine the format of the data set member attribute definition file. The fifth column (Coordsys) is used for two purposes. For a theme it specifies the spatial co-ordinate system of the data set member. The acronym "dd" means decimal degrees and is the recommended spatial co-ordinate system for INSROP GIS. The coordsys information is in some cases used by INSROP GIS to check that a theme in a projected View is stored as decimal degrees (However, it is the user's responsibility to only include themes with similar co-ordinates systems in a View). For a table it is used to provide the extension of the table file name, which is used to identify the table format. Only the first column is mandatory, the other ones are optional.

These files are not required for all data sets. If you have many similar data sets in a folder, e.g. only separated in time, and you want to use a .def file for documentary purposes, you may use "All" in the Theme-ID column and "alias.fld" as Aliasfile. You may also use the same data set definition file for several data set members.

__________

See also

Data set member attribute definition files