The $N8601H format writes
ISO 8601 durations, intervals, and datetimes in the following forms,
omitting components in the P
nY
nM
nDT
nH
nM
nS form and using a hyphen
( - ) to represent omitted components in the datetime form:
-
-
-
P
nY
nM
nDT
nH
nM
nS/
yyyy-mm-ddT
hh:mm:ss
-
yyyy-mm-ddT
hh:mm:ssT/P
nY
nM
nDT
nH
nM
nS
-
yyyy-mm-ddT
hh:mm:ss/
yyyy-mm-ddT
hh:mm:ss
Omitted datetime components
are always displayed; they are never truncated.