I always interpreted that as being instruction in the actual airplane, (which I do, as PIC during base training) not the sim. Do you have to keep on file your classroom instruction, procedure trainers, CSS's and FBS's too? Where do you draw the line?
The FAA requires that any instruction be recorded....as far as I know, 'how' this is done is not specified (i,e, in the instructors logbook, company training records, etc.). But, it is required that al this be recorded...each session, contents of each session, time for this, any endorsements, recommendations for checks....everything.
This is all covered by the training files kept by the employer as they keep copies of the student files aswell.