Question E2C02:
Which of the following file formats is used for exchanging amateur radio log data?  

Choices:  
A: NEC  
B: ARLD  
C: ADIF  
D: OCF    

Correct Answer is  C: ADIF  

Correct answer: C — ADIF

Why C is correct
- ADIF stands for Amateur Data Interchange Format.
- It is the standard, widely supported format for exchanging amateur radio log data between logging programs and online services.
- Files typically use the .adi extension and contain QSO fields like callsign, date/time, band, mode, and reports.

Why the others are incorrect
- A: NEC — Numerical Electromagnetics Code; an antenna modeling format (e.g., used by EZNEC/4NEC2), not a logging data exchange format.
- B: ARLD — An ARRL bulletin designator (e.g., ARLD0xx for DX bulletins), not a file format for logs.
- D: OCF — Off-Center-Fed (as in OCF dipole), a type of antenna, not a data format.

Rules of thumb
- For exchanging logs between programs/services, think “ADIF.”
- For contest log submissions, another common format is “Cabrillo,” but ADIF is the general-purpose interchange format.