Club Log accepts any valid ADIF file, but only uses some of the fields for reasons of economy of storage and processing.
The fields Club Log uses are those that it requires to perform its calculations, produce charts and so forth. Many ancillary comments or records in your ADIF are possible, as per the ADIF specification, but these are skipped during upload. This is one of the reasons that Club Log's own ADIF download function does not give you your original ADIF file back.
Here is a list of the ADIF fields Club Log uses:
- TIME_OFF (this is stored independently and used for log matching as well as ADIF exports)
- GRIDSQUARE [note that this is only set if the Club Log user sets a locator on Settings > Locators, and it is not stored per QSO]