The Zip file contains a suite of up to 7 xml files named as follows:
Hospital Closed dd-MMM-yyyy.xml
Hospital Open dd-MMM-yyyy.xml
General Closed dd-MMM-yyyy.xml
General Open dd-MMM-yyyy.xml
Combined Closed dd-MMM-yyyy.xml
Combined Open dd-MMM-yyyy.xml
Funds dd-MMM-yyyy.xml

dd-MMM-yyyy denotes the date of file extract in the format, e.g. 28-Mar-2019
Files with "Open" in their titles contain only products that are Open to new members.
Files with "Closed" in their titles contain only products that are Closed to new members.
Files with "Hospital" in their titles contain products that provide Hospital cover.
Files with "General" in their titles contain products that provide General Treatment or 'extras' cover.
Files with "Combined" in their titles contain products that provide cover for both Hospital and General Treatment. 
Note that 'Ambulance Only' products are General products that provide Ambulance cover and no other general treatments. 
The product xml files may contain significant numbers of entries - the largest is likely to hold in the region of up to 20000 entries.

The Funds xml file contains information about each of the health insurers that publish products on PrivateHealth.gov.au.

The zip file also contains an xml schema files, suffixed .xsd, as follows:  
PHOLSchema-V3.1.xsd - describes the structure of products published after 01-April-2019.  
The PHOLSchema-V3.1.xsd file includes the content of the accompanying PHOL-Lists-V3.1.xsd file.  
Of necessity, the schema files are reasonably complex documents.  
All fund records in the Fund.xml file and all product records in the Hospital, General and Combined files are conformant with this schema.  

The PHOLSchema-V3.1.xsd released in the 3rd quarter of 2021 contains some enhancements to support the changes introduced by the 
Private Health Insurance (Complying Product) (Age of Dependants) Amendment Rules 2021. 
Specifically, the Fund element contains an additional, optional, FundDependants sub-element that allows Funds to describe the types of dependants they cover and any associated age limits.
The Product element now allows a choice of how a Fund may specify who is covered by a particular product. Either by using the existing Scale element or instead by providing a new WhoIsCovered element.
This latter allows a more precise definition of coverage. All products have been converted to use the new WhoIsCovered element in time for the 1 April 2022 rate rise.

Two additional Comma-separated values (CSV) files may also be present, as follows:
Fund Changes dd-MMM-yyyy.csv  - contains a summary list of Funds that have been Added, Changed or Removed since the previous upload to the data.gov.au site.
Product Changes dd-MMM-yyyy.csv  - contains a summary list of Products that have been Added, Changed or Removed since the previous upload to the data.gov.au site.

Another CSV file has been added to the zip as of 01-July-2020 - this includes details of the Private Hospitals with which the various health insurers have agreements.
This file contains one row per Agreement Hospital and includes the Provider code, name, address and location of the Hospital. A value of 1 for the IsDay column indicates the Hospital is a day hospital only and does not offer overnight stays.
Each row also contains a column for each health insurer - identified by their respective 3-character fund code. A value of 1 in this column indicates the insurer in question has an agreement with that Hospital.
This file is named as follows:
Agreement Hospitals dd-MMM-yyyy.csv

