As a rule you should avoid using the zero value in your lookups file, but under some cases zero can be useful. Zero can be used if you were only interested in a few key import values in a field of your data. If you were only concerned about a portion of the citations, and only wanted to know a vehicle citation was issued for any other violations this could be done with a zero lookup value. We could set the key values for moving violations in the changes file (*.cng) and set the values for the Lookup file (*.lus) labeling zero for “Unknown Citation”.
Here is an example:
We enter the following into the changes file.
VEH1CITATION 1 622A
VEH1CITATION 2 693A
VEH1CITATION 3 1381A1
The following lines are already in our lookup file
0 Unkown Citation
1 Traffic control device
2 Serious moving violation
The importer would store a value of 3 in the Intersection Magic database for each "1381A1" that was imported for the VEH1CITATION field.
If the importer encountered a value of 4139A in the citation field it would check the changes file. The value is not listed in the file. The importer would store 0 in the database for that field, and make an entry in the CGFAIL log.
We would know that a citation is entered for that vehicle, but we would not know what the citation was for.