Hello,
I have the following behaviour on my system, with version 2.10.2-2 and
bsdmainutils 8.0.2:
lfousse@bourrasque:~% LANG=POSIX LC_ALL=POSIX cal
December 2009
Su Mo Tu We Th Fr Sa
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
If I understand things correctly the expected result in this case is
to have weeks starting on monday.
Laurent.