How do you record your dip slide results?

Hi guys!!

We had a legionella team come round and do our testing and were recommended to do dip slides. He sent us some forms to record the dip slide results after but I don't really understand them and they are not explained.

The columns are as follows
Date
Surgery
Pass/Fail
Purging date
Pass/fail
Photo Y/N

We have taken photos of the results and have them recorded. I don't understand the 'purging' bit? and why it asks for a pass/fail twice?

Any help would be appreciated!