To get an accurate interpretation of the reguations without suppositions, I recommend you look up the following FARs

Subpart Q—Flight Time Limitations and Rest Requirements: Domestic Operations
Beginning with FAR Part § 121.470
Source: Docket No. 23634, 50 FR 29319, July 18, 1985, unless otherwise noted

Subpart R—Flight Time Limitations: Flag Operations
Beginning with FAR Part § 121.480
Source: Docket No. 6258, 29 FR 19217, Dec. 31, 1964; 30 FR 3639, Mar. 19 1965, unless otherwise noted.


Subpart S—Flight Time Limitations: Supplemental Operations
Beginning with FAR Part § 121.500
Source: Docket No. 6258, 29 FR 19218, Dec. 31, 1964; 30 FR 3639, Mar. 19 1965, unless otherwise noted.

You cant go wrong by looking up the FARs.