Creation of Dates | Zend_Date Programmer's Reference Guide | Working Examples

# Constants for General Date Functions

Whenever a Zend_Date method has a $parts parameter, one of the constants below can be used as the argument for that parameter, in order to select a specific part of a date or indicate the date format used or desired (e.g. RFC 822).

# Using Constants

For example, the constant `Zend_Date::HOUR` can be used in the ways shown below. When working with days of the week, calendar dates, hours, minutes, seconds, and any other date parts that are expressed differently when in different parts of the world, the object's timezone will automatically be used to compute the correct value, even though the internal timestamp is the same for the same moment in time, regardless of the user's physical location in the world. Regardless of the units involved, output must be expressed either as GMT or UTC or localized to a locale. The example output below reflects localization to Europe/GMT+1 hour (e.g. Germany, Austria, France).

Operations Involving Zend_Date::HOUR
Method | Description | Original date | Result
--- | --- | --- | ---
get(Zend_Date::HOUR) | Output of the hour | 2009-02-13T14:53:27+01:00 | 14
set(12, Zend_Date::HOUR) | Set new hour | 2009-02-13T14:53:27+01:00 | 2009-02-13T12:53:27+01:00
add(12, Zend_Date::HOUR) | Add hours | 2009-02-13T14:53:27+01:00 | 2009-02-14T02:53:27+01:00
sub(12, Zend_Date::HOUR) | Subtract hours | 2009-02-13T14:53:27+01:00 | 2009-02-13T02:53:27+01:00
compare(12, Zend_Date::HOUR) | Compare hour, returns 0, 1 or -1 | 2009-02-13T14:53:27+01:00 | 1 (if object > argument)
copy(Zend_Date::HOUR) | Copies only the hour part | 2009-02-13T14:53:27+01:00 | 1970-01-01T14:00:00+01:00
equals(14, Zend_Date::HOUR) | Compares the hour, returns `TRUE` or `FALSE` | 2009-02-13T14:53:27+01:00 | `TRUE`
isEarlier(12, Zend_Date::HOUR) | Compares the hour, returns `TRUE` or `FALSE` | 2009-02-13T14:53:27+01:00 | `TRUE`
isLater(12, Zend_Date::HOUR) | Compares the hour, returns `TRUE` or `FALSE` | 2009-02-13T14:53:27+01:00 | `FALSE`

# List of All Constants

Each part of a date or time has a unique constant in Zend_Date. All constants supported by Zend_Date are listed below.

Day Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::DAY` | Day (as number, two digits) | 2009-02-13T14:53:27+01:00 | 13
`Zend_Date::DAY_SHORT` | Day (as number, one or two digits) | 2009-02-06T14:53:27+01:00 | 6
`Zend_Date::WEEKDAY` | Weekday (Name of the day, localized, complete) | 2009-02-13T14:53:27+01:00 | Friday
`Zend_Date::WEEKDAY_SHORT` | Weekday (Name of the day, localized, abbreviated, two to four chars) | 2009-02-13T14:53:27+01:00 | Fri for Friday
`Zend_Date::WEEKDAY_NAME` | Weekday (Name of the day, localized, abbreviated, one or two chars) | 2009-02-13T14:53:27+01:00 | Fr for Friday
`Zend_Date::WEEKDAY_NARROW` | Weekday (Name of the day, localized, abbreviated, one char) | 2009-02-13T14:53:27+01:00 | F for Friday
`Zend_Date::WEEKDAY_DIGIT` | Weekday (0 = Sunday, 6 = Saturday) | 2009-02-13T14:53:27+01:00 | 5 for Friday
`Zend_Date::WEEKDAY_8601` | Weekday according to ISO 8601 (1 = Monday, 7 = Sunday) | 2009-02-13T14:53:27+01:00 | 5 for Friday
`Zend_Date::DAY_OF_YEAR` | Day (as a number, one or two digits) | 2009-02-13T14:53:27+01:00 | 43
`Zend_Date::DAY_SUFFIX` | English addendum for the day (st, nd, rd, th) | 2009-02-13T14:53:27+01:00 | th

Week Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::WEEK` | Week (as number, 1-53) | 2009-02-13T14:53:27+01:00 | 8

Month Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::MONTH_NAME` | Month (Name of the month, localized, complete) | 2009-02-13T14:53:27+01:00 | February
`Zend_Date::MONTH_NAME_SHORT` | Month (Name of the month, localized, abbreviated, two to four chars) | 2009-02-13T14:53:27+01:00 | Feb
`Zend_Date::MONTH_NAME_NARROW` | Month (Name of the month, localized, abbreviated, one or two chars) | 2009-02-13T14:53:27+01:00 | F
`Zend_Date::MONTH` | Month (Number of the month, two digits) | 2009-02-13T14:53:27+01:00 | 02
`Zend_Date::MONTH_SHORT` | Month (Number of the month, one or two digits) | 2009-02-13T14:53:27+01:00 | 2
`Zend_Date::MONTH_DAYS` | Number of days for this month (number) | 2009-02-13T14:53:27+01:00 | 28

Year Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::YEAR` | Year (number) | 2009-02-13T14:53:27+01:00 | 2009
`Zend_Date::YEAR_8601` | Year according to ISO 8601 (number) | 2009-02-13T14:53:27+01:00 | 2009
`Zend_Date::YEAR_SHORT` | Year (number, two digits) | 2009-02-13T14:53:27+01:00 | 09
`Zend_Date::YEAR_SHORT_8601` | Year according to ISO 8601 (number, two digits) | 2009-02-13T14:53:27+01:00 | 09
`Zend_Date::LEAPYEAR` | Is the year a leap year? (`TRUE` or `FALSE`) | 2009-02-13T14:53:27+01:00 | `FALSE`

Time Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::HOUR` | Hour (00-23, two digits) | 2009-02-13T14:53:27+01:00 | 14
`Zend_Date::HOUR_SHORT` | Hour (0-23, one or two digits) | 2009-02-13T14:53:27+01:00 | 14
`Zend_Date::HOUR_SHORT_AM` | Hour (1-12, one or two digits) | 2009-02-13T14:53:27+01:00 | 2
`Zend_Date::HOUR_AM` | Hour (01-12, two digits) | 2009-02-13T14:53:27+01:00 | 02
`Zend_Date::MINUTE` | Minute (00-59, two digits) | 2009-02-13T14:53:27+01:00 | 53
`Zend_Date::MINUTE_SHORT` | Minute (0-59, one or two digits) | 2009-02-13T14:03:27+01:00 | 3
`Zend_Date::SECOND` | Second (00-59, two digits) | 2009-02-13T14:53:27+01:00 | 27
`Zend_Date::SECOND_SHORT` | Second (0-59, one or two digits) | 2009-02-13T14:53:07+01:00 | 7
`Zend_Date::MILLISECOND` | Millisecond (theoretically infinite) | 2009-02-06T14:53:27.20546 | 20546
`Zend_Date::MERIDIEM` | Time of day (forenoon or afternoon) | 2009-02-13T14:53:27+01:00 | afternoon
`Zend_Date::SWATCH` | Swatch Internet Time | 2009-02-13T14:53:27+01:00 | 620

Timezone Constants
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::TIMEZONE` | Name der time zone (string, abbreviated) | 2009-02-13T14:53:27+01:00 | CET
`Zend_Date::TIMEZONE_NAME` | Name of the time zone (string, complete) | 2009-02-13T14:53:27+01:00 | Europe/Paris
`Zend_Date::TIMEZONE_SECS` | Difference of the time zone to GMT in seconds (integer) | 2009-02-13T14:53:27+01:00 | 3600 (seconds to GMT)
`Zend_Date::GMT_DIFF` | Difference to GMT in seconds (string) | 2009-02-13T14:53:27+01:00 | +0100
`Zend_Date::GMT_DIFF_SEP` | Difference to GMT in seconds (string, separated) | 2009-02-13T14:53:27+01:00 | +01:00
`Zend_Date::DAYLIGHT` | Summer time or Winter time? (`TRUE` or `FALSE`) | 2009-02-13T14:53:27+01:00 | `FALSE`

Date Format Constants (formats include timezone)
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::ISO_8601` | Date according to ISO 8601 (string, complete) | 2009-02-13T14:53:27+01:00 | 2009-02-13T14:53:27+01:00
`Zend_Date::RFC_2822` | Date according to RFC 2822 (string) | 2009-02-13T14:53:27+01:00 | Fri, 13 Feb 2009 14:53:27 +0100
`Zend_Date::TIMESTAMP` | » Unix time (seconds since 1.1.1970, mixed) | 2009-02-13T14:53:27+01:00 | 1234533207
`Zend_Date::ATOM` | Date according to ATOM (string) | 2009-02-13T14:53:27+01:00 | 2009-02-13T14:53:27+01:00
`Zend_Date::COOKIE` | Date for Cookies (string, for Cookies) | 2009-02-13T14:53:27+01:00 | Friday, 13-Feb-09 14:53:27 Europe/Paris
`Zend_Date::RFC_822` | Date according to RFC 822 (string) | 2009-02-13T14:53:27+01:00 | Fri, 13 Feb 09 14:53:27 +0100
`Zend_Date::RFC_850` | Date according to RFC 850 (string) | 2009-02-13T14:53:27+01:00 | Friday, 13-Feb-09 14:53:27 Europe/Paris
`Zend_Date::RFC_1036` | Date according to RFC 1036 (string) | 2009-02-13T14:53:27+01:00 | Fri, 13 Feb 09 14:53:27 +0100
`Zend_Date::RFC_1123` | Date according to RFC 1123 (string) | 2009-02-13T14:53:27+01:00 | Fri, 13 Feb 2009 14:53:27 +0100
`Zend_Date::RSS` | Date for RSS Feeds (string) | 2009-02-13T14:53:27+01:00 | Fri, 13 Feb 2009 14:53:27 +0100
`Zend_Date::W3C` | Date for HTML or HTTP according to W3C (string) | 2009-02-13T14:53:27+01:00 | 2009-02-13T14:53:27+01:00

Especially note `Zend_Date::DATES`, since this format specifier has a unique property within Zend_Date as an input format specifier. When used as an input format for $part, this constant provides the most flexible acceptance of a variety of similar date formats. Heuristics are used to automatically extract dates from an input string and then "fix" simple errors in dates (if any), such as swapping of years, months, and days, when possible.

Date and Time Formats (format varies by locale)
Constant | Description | Date | Result
--- | --- | --- | ---
`Zend_Date::ERA` | Epoch (string, localized, abbreviated) | 2009-02-13T14:53:27+01:00 | AD (anno Domini)
`Zend_Date::ERA_NAME` | Epoch (string, localized, complete) | 2009-02-13T14:53:27+01:00 | anno domini (anno Domini)
`Zend_Date::DATES` | Standard date (string, localized, default value). | 2009-02-13T14:53:27+01:00 | 13.02.2009
`Zend_Date::DATE_FULL` | Complete date (string, localized, complete) | 2009-02-13T14:53:27+01:00 | Friday, 13. February 2009
`Zend_Date::DATE_LONG` | Long date (string, localized, long) | 2009-02-13T14:53:27+01:00 | 13. February 2009
`Zend_Date::DATE_MEDIUM` | Normal date (string, localized, normal) | 2009-02-13T14:53:27+01:00 | 13.02.2009
`Zend_Date::DATE_SHORT` | Abbreviated Date (string, localized, abbreviated) | 2009-02-13T14:53:27+01:00 | 13.02.09
`Zend_Date::TIMES` | Standard time (string, localized, default value) | 2009-02-13T14:53:27+01:00 | 14:53:27
`Zend_Date::TIME_FULL` | Complete time (string, localized, complete) | 2009-02-13T14:53:27+01:00 | 14:53 Uhr CET
`Zend_Date::TIME_LONG` | Long time (string, localized, Long) | 2009-02-13T14:53:27+01:00 | 14:53:27 CET
`Zend_Date::TIME_MEDIUM` | Normal time (string, localized, normal) | 2009-02-13T14:53:27+01:00 | 14:53:27
`Zend_Date::TIME_SHORT` | Abbreviated time (string, localized, abbreviated) | 2009-02-13T14:53:27+01:00 | 14:53
`Zend_Date::DATETIME` | Standard date with time (string, localized, default value). | 2009-02-13T14:53:27+01:00 | 13.02.2009 14:53:27
`Zend_Date::DATETIME_FULL` | Complete date with time (string, localized, complete) | 2009-02-13T14:53:27+01:00 | Friday, 13. February 2009 14:53 Uhr CET
`Zend_Date::DATETIME_LONG` | Long date with time (string, localized, long) | 2009-02-13T14:53:27+01:00 | 13. February 2009 14:53:27 CET
`Zend_Date::DATETIME_MEDIUM` | Normal date with time (string, localized, normal) | 2009-02-13T14:53:27+01:00 | 13.02.2009 14:53:27
`Zend_Date::DATETIME_SHORT` | Abbreviated date with time (string, localized, abbreviated) | 2009-02-13T14:53:27+01:00 | 13.02.09 14:53

# Self-Defined OUTPUT Formats with ISO

If you need a date format not shown above, then use a self-defined format composed from the ISO format token specifiers below. The following examples illustrate the usage of constants from the table below to create self-defined ISO formats. The format length is unlimited. Also, multiple usage of format constants is allowed.

The accepted format specifiers can be changed from ISO Format to PHP's date format if you are more comfortable with it. However, not all formats defined in the ISO norm are supported with PHP's date format specifiers. Use the Zend_Date::setOptions(array('format_type' => 'php')) method to switch Zend_Date methods from supporting ISO format specifiers to PHP date() type specifiers (see Self-Defined OUTPUT Formats Using PHP's date() Format Specifiers below).

Example #1 Self-Defined ISO Formats

1. $locale = new Zend_Locale('de_AT');
2. $date = new Zend_Date(1234567890, false, $locale);
3. print $date->toString("'Era:GGGG='GGGG, ' Date:yy.MMMM.dd'yy.MMMM.dd");

Constants for ISO 8601 Date Output
Constant | Description | Corresponds best to | Result
--- | --- | --- | ---
G | Epoch, localized, abbreviated | `Zend_Date::ERA` | AD
GG | Epoch, localized, abbreviated | `Zend_Date::ERA` | AD
`GGG` | Epoch, localized, abbreviated | `Zend_Date::ERA` | AD
`GGGG` | Epoch, localized, complete | `Zend_Date::ERA_NAME` | anno domini
`GGGGG` | Epoch, localized, abbreviated | `Zend_Date::ERA` | a
y | Year, at least one digit | `Zend_Date::YEAR` | 9
yy | Year, at least two digit | `Zend_Date::YEAR_SHORT` | 09
yyy | Year, at least three digit | `Zend_Date::YEAR` | 2009
yyyy | Year, at least four digit | `Zend_Date::YEAR` | 2009
yyyyy | Year, at least five digit | `Zend_Date::YEAR` | 02009
Y | Year according to ISO 8601, at least one digit | `Zend_Date::YEAR_8601` | 9
YY | Year according to ISO 8601, at least two digit | `Zend_Date::YEAR_SHORT_8601` | 09
`YYY` | Year according to ISO 8601, at least three digit | `Zend_Date::YEAR_8601` | 2009
`YYYY` | Year according to ISO 8601, at least four digit | `Zend_Date::YEAR_8601` | 2009
`YYYYY` | Year according to ISO 8601, at least five digit | `Zend_Date::YEAR_8601` | 02009
M | Month, one or two digit | `Zend_Date::MONTH_SHORT` | 2
MM | Month, two digit | `Zend_Date::MONTH` | 02
`MMM` | Month, localized, abbreviated | `Zend_Date::MONTH_NAME_SHORT` | Feb
`MMMM` | Month, localized, complete | `Zend_Date::MONTH_NAME` | February
`MMMMM` | Month, localized, abbreviated, one digit | `Zend_Date::MONTH_NAME_NARROW` | F
w | Week, one or two digit | `Zend_Date::WEEK` | 5
ww | Week, two digit | `Zend_Date::WEEK` | 05
d | Day of the month, one or two digit | `Zend_Date::DAY_SHORT` | 9
dd | Day of the month, two digit | `Zend_Date::DAY` | 09
D | Day of the year, one, two or three digit | `Zend_Date::DAY_OF_YEAR` | 7
DD | Day of the year, two or three digit | `Zend_Date::DAY_OF_YEAR` | 07
`DDD` | Day of the year, three digit | `Zend_Date::DAY_OF_YEAR` | 007
E | Day of the week, localized, abbreviated, one char | `Zend_Date::WEEKDAY_NARROW` | M
EE | Day of the week, localized, abbreviated, two or more chars | `Zend_Date::WEEKDAY_NAME` | Mo
`EEE` | Day of the week, localized, abbreviated, three chars | `Zend_Date::WEEKDAY_SHORT` | Mon
`EEEE` | Day of the week, localized, complete | `Zend_Date::WEEKDAY` | Monday
`EEEEE` | Day of the week, localized, abbreviated, one digit | `Zend_Date::WEEKDAY_NARROW` | M
e | Number of the day, one digit | `Zend_Date::WEEKDAY_DIGIT` | 4
ee | Number of the day, two digit | `Zend_Date::WEEKDAY_NARROW` | 04
a | Time of day, localized | `Zend_Date::MERIDIEM` | vorm.
h | Hour, (1-12), one or two digit | `Zend_Date::HOUR_SHORT_AM` | 2
hh | Hour, (01-12), two digit | `Zend_Date::HOUR_AM` | 02
H | Hour, (0-23), one or two digit | `Zend_Date::HOUR_SHORT` | 2
HH | Hour, (00-23), two digit | `Zend_Date::HOUR` | 02
m | Minute, (0-59), one or two digit | `Zend_Date::MINUTE_SHORT` | 2
mm | Minute, (00-59), two digit | `Zend_Date::MINUTE` | 02
s | Second, (0-59), one or two digit | `Zend_Date::SECOND_SHORT` | 2
ss | Second, (00-59), two digit | `Zend_Date::SECOND` | 02
S | Millisecond | `Zend_Date::MILLISECOND` | 20536
z | Time zone, localized, abbreviated | `Zend_Date::TIMEZONE` | `CET`
zz | Time zone, localized, abbreviated | `Zend_Date::TIMEZONE` | `CET`
zzz | Time zone, localized, abbreviated | `Zend_Date::TIMEZONE` | `CET`
zzzz | Time zone, localized, complete | `Zend_Date::TIMEZONE_NAME` | Europe/Paris
Z | Difference of time zone | `Zend_Date::GMT_DIFF` | +0100
ZZ | Difference of time zone | `Zend_Date::GMT_DIFF` | +0100
`ZZZ` | Difference of time zone | `Zend_Date::GMT_DIFF` | +0100
`ZZZZ` | Difference of time zone, separated | `Zend_Date::GMT_DIFF_SEP` | +01:00
A | Milliseconds from the actual day | `Zend_Date::MILLISECOND` | 20563

> Note: Note that the default ISO format differs from PHP's format which can be irritating if you have not used in previous. Especially the format specifiers for Year and Minute are often not used in the intended way.
> For year there are two specifiers available which are often mistaken. The Y specifier for the ISO year and the y specifier for the real year. The difference is small but significant. Y calculates the ISO year, which is often used for calendar formats. See for example the 31. December 2007. The real year is 2007, but it is the first day of the first week in the week 1 of the year 2008. So, if you are using 'dd.MM.yyyy' you will get '31.December.2007' but if you use 'dd.MM.YYYY' you will get '31.December.2008'. As you see this is no bug but a expected behaviour depending on the used specifiers.
> For minute the difference is not so big. ISO uses the specifier m for the minute, unlike PHP which uses i. So if you are getting no minute in your format check if you have used the right specifier.

# Self-Defined OUTPUT Formats Using PHP's date() Format Specifiers

If you are more comfortable with PHP's date format specifier than with ISO format specifiers, then you can use the Zend_Date::setOptions(array('format_type' => 'php')) method to switch Zend_Date methods from supporting ISO format specifiers to PHP date() type specifiers. Afterwards, all format parameters must be given with » PHP's date() format specifiers. The PHP date format lacks some of the formats supported by the ISO Format, and vice-versa. If you are not already comfortable with it, then use the standard ISO format instead. Also, if you have legacy code using PHP's date format, then either manually convert it to the ISO format using Zend_Locale_Format::convertPhpToIsoFormat(), or use setOptions(). The following examples illustrate the usage of constants from the table below to create self-defined formats.

Example #2 Self-Defined Formats with PHP Specifier

1. $locale = new Zend_Locale('de_AT');
2. Zend_Date::setOptions( array ('format_type' => 'php'));
3. $date = new Zend_Date(1234567890, false, $locale);
5. // outputs something like 'February 16, 2007, 3:36 am'
6. print $date->toString('F j, Y, g:i a');
8. print $date->toString("'Format:D M j G:i:s T Y='D M j G:i:s T Y");

Important

# PHP Date format and using constants

It is important to note that Zend_Date's constants are using the ISO notation. This means, that when you set Zend_Date to use the PHP notation, you should not use Zend_Date's constants, but define the wished format manually. If you don't follow this recommendation, you can get unexpected results.

The following table shows the list of PHP date format specifiers with their equivalent Zend_Date constants and CLDR and ISO equivalent format specifiers. In most cases, when the CLDR and ISO format does not have an equivalent format specifier, the PHP format specifier is not altered by Zend_Locale_Format::convertPhpToIsoFormat(), and the Zend_Date methods then recognize these "peculiar" PHP format specifiers, even when in the default "ISO" format mode.

Constants for PHP Date Output
Constant | Description | Corresponds best to | closest CLDR equivalent | Result
--- | --- | --- | --- | ---
d | Day of the month, two digit | `Zend_Date::DAY` | dd | 09
D | Day of the week, localized, abbreviated, three digit | `Zend_Date::WEEKDAY_SHORT` | `EEE` | Mon
j | Day of the month, one or two digit | `Zend_Date::DAY_SHORT` | d | 9
l (lowercase L) | Day of the week, localized, complete | `Zend_Date::WEEKDAY` | `EEEE` | Monday
N | Number of the weekday, one digit | `Zend_Date::WEEKDAY_8601` | e | 4
S | English suffixes for day of month, two chars | no equivalent | no equivalent | st
w | Number of the weekday, 0=sunday, 6=saturday | `Zend_Date::WEEKDAY_DIGIT` | no equivalent | 4
z | Day of the year, one, two or three digit | `Zend_Date::DAY_OF_YEAR` | D | 7
W | Week, one or two digit | `Zend_Date::WEEK` | w | 5
F | Month, localized, complete | `Zend_Date::MONTH_NAME` | `MMMM` | February
m | Month, two digit | `Zend_Date::MONTH` | MM | 02
M | Month, localized, abbreviated | `Zend_Date::MONTH_NAME_SHORT` | `MMM` | Feb
n | Month, one or two digit | `Zend_Date::MONTH_SHORT` | M | 2
t | Number of days per month, one or two digits | `Zend_Date::MONTH_DAYS` | no equivalent | 30
L | Leapyear, boolean | `Zend_Date::LEAPYEAR` | no equivalent | `TRUE`
o | Year according to ISO 8601, at least four digit | `Zend_Date::YEAR_8601` | `YYYY` | 2009
Y | Year, at least four digit | `Zend_Date::YEAR` | yyyy | 2009
y | Year, at least two digit | `Zend_Date::YEAR_SHORT` | yy | 09
a | Time of day, localized | `Zend_Date::MERIDIEM` | a (sort of, but likely to be uppercase) | vorm.
A | Time of day, localized | `Zend_Date::MERIDIEM` | a (sort of, but no guarantee that the format is uppercase) | VORM.
B | Swatch internet time | `Zend_Date::SWATCH` | no equivalent | 1463
g | Hour, (1-12), one or two digit | `Zend_Date::HOUR_SHORT_AM` | h | 2
G | Hour, (0-23), one or two digit | `Zend_Date::HOUR_SHORT` | H | 2
h | Hour, (01-12), two digit | `Zend_Date::HOUR_AM` | hh | 02
H | Hour, (00-23), two digit | `Zend_Date::HOUR` | HH | 02
i | Minute, (00-59), two digit | `Zend_Date::MINUTE` | mm | 02
s | Second, (00-59), two digit | `Zend_Date::SECOND` | ss | 02
e | Time zone, localized, complete | `Zend_Date::TIMEZONE_NAME` | zzzz | Europe/Paris
I | Daylight | `Zend_Date::DAYLIGHT` | no equivalent | 1
O | Difference of time zone | `Zend_Date::GMT_DIFF` | Z or ZZ or `ZZZ` | +0100
P | Difference of time zone, separated | `Zend_Date::GMT_DIFF_SEP` | `ZZZZ` | +01:00
T | Time zone, localized, abbreviated | `Zend_Date::TIMEZONE` | z or zz or zzz | `CET`
Z | Time zone offset in seconds | `Zend_Date::TIMEZONE_SECS` | no equivalent | 3600
c | Standard Iso format output | `Zend_Date::ISO_8601` | no equivalent | 2004-02-13T15:19:21+00:00
r | Standard Rfc 2822 format output | `Zend_Date::RFC_2822` | no equivalent | Thu, 21 Dec 2000 16:01:07 +0200
U | Unix timestamp | `Zend_Date::TIMESTAMP` | no equivalent | 15275422364

Creation of Dates | Zend_Date Programmer's Reference Guide | Working Examples