ISO 8601 durations

HMSTime.from_iso8601() and to_iso8601() support full ISO 8601 duration syntax.

Time only

from hmscalc import HMSTime

HMSTime.from_iso8601("PT1H30M15S")  # "1:30:15"
HMSTime.from_iso8601("PT30M")       # "0:30:00"

Date components

HMSTime.from_iso8601("P1D")         # 24:00:00
HMSTime.from_iso8601("P1W")         # 168:00:00 (1 week)
HMSTime.from_iso8601("P1DT2H")     # 26:00:00

Nominal months and years

Calendar months/years are converted using fixed nominal lengths:

Component	Seconds
P1M	30 days
P1Y	365 days

This matches hmscalc's second-based duration model. For calendar-accurate month arithmetic, combine with hmscalc.dates instead.

Output

HMSTime("24:00:00").to_iso8601()   # "P1D"
HMSTime("168:00:00").to_iso8601()  # "P1W"
HMSTime("26:00:00").to_iso8601()   # "P1DT2H"

Limitations

• P1W cannot be combined with other date/time components (ISO 8601 rule).
• P1M before T is a month; PT1M after T is a minute.