Gnumeric can be told to store a time duration and not treat it as a time of day (TOD). The lack of this ability in Libroffice Calc constitutes a defect in requirements analysis.
(In reply to Jack WAUGH from comment #0) > Gnumeric can be told to store a time duration and not treat it as a time of > day (TOD). The lack of this ability in Libroffice Calc constitutes a defect > in requirements analysis. Formatting "time durations" in Calc is done by format code "[HH]:MM". Isn't that what you are looking for? Ref.: https://help.libreoffice.org/latest/en-US/text/shared/01/05020301.html?DbPAR=SHARED#bm_id3153514 - Section Time Formats
OK, the format code you give works, and still works if :SS is appended to the end. So no analysis, design, or code change is needed. The answer at https://ask.libreoffice.org/en/question/139750/time-as-duration/ mislead me and I think it should be changed to point out what you have here pointed out. The relevant doc and the solution.