Records primarily contain reports on site contamination in order to assess whether the site required cleaning and being added to a site register. Examples of contamination include underground storage tanks (USTs), discharges to land and waterways, and ex-industrial sites re-zoned by council.
Certain files contain extensive histories of the specific site outside of the contamination scope and are valuable historical records.
The prefix is followed by a number representing a region within the Manawatū-Whanganui Region (index below):
01 - Horowhenua District
02 - Manawatū District
03 - Palmerston North City
04 - Tararua District
05 - Rangitīkei District
06 - Whanganui City
07 - Ruapehu District
The last alpha character is contiguous in the order of record creation (A to Z, then AA to AB, then BA to BZ, etc.).