they ARE CaSe sEnsItIVe:
DAYS
d - day of the month 2 digits (01-31)
j - day of the month (1-31)
D - 3 letter day (Mon - Sun)
l - full name of day (Monday - Sunday)
N - 1=Monday, 2=Tuesday, etc (1-7)
S - suffix for date (st, nd, rd)
w - 0=Sunday, 1=Monday (0-6)
z - day of the year (1=365)
WEEK
W - week of the year (1-52)
MONTH
F - Full name of month (January - December)
m - 2 digit month number (01-12)
n - month number (1-12)
M - 3 letter month (Jan - Dec)
t - Days in the month (28-31)
YEAR
L - leap year (0 no, 1 yes)
o - ISO-8601 year number (Ex. 1979, 2006)
Y - four digit year (Ex. 1979, 2006)
y - two digit year (Ex. 79, 06)
TIME
a - am or pm
A - AM or PM
B - Swatch Internet time (000 - 999)
g - 12 hour (1-12)
G - 24 hour c (0-23)
h - 2 digit 12 hour (01-12)
H - 2 digit 24 hour (00-23)
i - 2 digit minutes (00-59)
s 0 2 digit seconds (00-59)
OTHER e - timezone (Ex: GMT, CST)
I - daylight savings (1=yes, 0=no)
O - offset GMT (Ex: 0200)
Z - offset in seconds (-43200 - 43200)
r - full RFC 2822 formatted date