30 seconds with google found: http://flighttraining.aopa.org/student_pilot/solo/faqs/

FAR 61.51(e)(4) says, "A student pilot may log pilot-in-command time
when the student pilot
(i) Is the sole occupant of the aircraft;
(ii) Has a current solo flight endorsement as required under [FAR] 61.87; and
(iii) Is undergoing training for a pilot certificate or rating.

Alan

Alan, you are better at google than I am.

Thanks.