DEFINING ATTRIBUTE LINKAGES

Both MapInfo and ArcInfo use relational databases.

Tables containing attributes and spatial features can be linked or joined based on a common data field.

Llinks or joins indicate that new attributes are added to spatial features in a data layer.

• Link: a connection between two tables using pointers between related records.
• Join: data from one table is physically added to the data of corresponding records in the second table.

 You should document the source tables involved in the linkage which did not originally belong to the spatial features.  For example:

• You have a spatial data layer of census enumeration areas with some demographic subject categories.
• You also have a table consisting of 2 columns: EA#, per capita alcohol consumption.
• Your problem solution involved relating per capita alcohol consumption to per capita income in each EA .
• You performed a database join in MapInfo to augment the census enumeration layer.
• In this section of the interim report you should describe this step.
• You should also adjust the data dictionary for the new census enumeration layer to include the attributes, including a reference to the source table.