SWI-Prolog offers the possibility to log the interaction with the 
user on a file.64A similar 
facility was added to Edinburgh C-Prolog by Wouter Jansweijer. 
All Prolog interaction, including warnings and tracer output, are 
written on the protocol file.
- protocol(+File)
- 
Start protocolling on file File. If there is already a 
protocol file open then close it first. If File exists it is 
truncated.
- protocola(+File)
- 
Equivalent to protocol/1, 
but does not truncate the File if it exists.
- noprotocol
- 
Stop making a protocol of the user interaction. Pending output is 
flushed on the file.
- protocolling(-File)
- 
True if a protocol was started with protocol/1 
or protocola/1 
and unifies File with the current protocol output file.