Walter - the 'sticky' at the top of this forum has lots of useful links, one of which is to JAA/JAR under "Regulatory Standards and Related Documents".
From the linked web site,
"JAR-MMEUMEL.OO1 Applicability 0 (a) Applicable Regulations.
blah blah blah
(3)
(c) "Calendar Day" A 24 hour period from
midnight to midnight based on either UTC or local time,
as selected by the operator.
(d) "Commencement of flight" The point when
an aircraft begins to move under its own power for the
purpose of preparing for take off.
(e) "Day of discovery" The calendar day that a
malfunction was recorded in the aircraft maintenance
recordlog book.
blah blah blah"
You may find the rest of your answers there.