Previous posts have said 100/30 is calendar month.
This may or may not be true.
Sometimes it is 30 consecutive days.
The FARs are very hard to apply to FedEx cuz we fly a very mixed schedule of 2 3 and 4 man cockpit and domestic and international.
Very often in the same month.
They seem to be crafted around the PAX guys that do ATL MXP ATL 4 times that month and then ATL LHR ATL 4 times the next month.
In the past, I have asked the union and company scheduling for some specifics but can get none.
What is a calendar day? Local? Zulu? 0130 to 0129 LBD?

some snippets of some POSSIBLE applicable FARs:
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§ 121.471 Flight time limitations and rest requirements: All flight crewmembers.
(1) 1,000 hours in any calendar year;
(2) 100 hours in any calendar month;
(3) 30 hours in any 7 consecutive days;

Flag
121.481 - Flight time limitations: One or two pilot crews.
This subpart prescribes flight time limitations and rest requirements for flag all-cargo operations....

§ 121.481 - Flight time limitations: One or two pilot crews.
(d) No pilot may fly more than 32 hours during any seven consecutive days, and each pilot must be relieved from all duty for at least 24 consecutive hours at least once during any seven consecutive days.
(e) No pilot may fly as a member of a crew more than 100 hours during any one calendar month.
(f) No pilot may fly as a member of a crew more than 1,000 hours during any 12-calendar-month period.

§ 121.483 - Flight time limitations: Two pilots and one additional flight crewmember.
(c) No pilot may fly as a flight crewmember more than -
(1) 120 hours during any 30 consecutive days;
(2) 300 hours during any 90 consecutive days; or
(3) 1,000 hours during any 12-calendar-month period.

§ 121.487 - Flight time limitations: Pilots not regularly assigned.
(a) Except as provided in paragraphs (b) through (e) of this section, a pilot who is not regularly assigned as a flight crewmember for an entire calendar month under § 121.483 or 121.485 may not fly more than 100 hours in any 30 consecutive days.
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extremely confusing to apply to our schedules