AOPA's Flight Training magazine for May 2005 has an article concerning
the new "Designated Pilot and Flight Engineer Examiners' Handbook.
http://afs600.faa.gov/ look on the right side for "Pilot examiner's
handbook."

p. 60 from the magazine
In the past, " FSDOs had instructed DPEs that unless it was reasonable
to expect to complete the test on the appointed day, the test was to be
rescheduled."
"better guidance appears now with the examiner authorized to elect,
with the applicant's concurrence, to begin the test anyway with the
intention of finishing on another day. However, when the test is
discontinued, the applicant must be issued a letter of discontinuance.