Release 10.1A: OpenEdge Deployment:
Startup Command and Parameter Reference

> ## Century Year Offset (-yy)

> Use Century Year Offset (`-yy`) to determine the start of the 100-year period in which a date with a two-digit year is valid.

> Operating system and syntax | UNIX Windows | `-yy` `n`
> Use with | Maximum value | Minimum value | Single-user default | Multi-user default
> Client Session, Database Server | – | – | 1950 | 1950

> ``n``

> A four-digit year (1990, for example). The default is 1950.

> Some OpenEdge applications reserve only two-digits for the year in the date format. When, for example, `-yy` is set at 1950, Progress determines if the two-digit year value is greater or less than 50. If the year is greater than 50, Progress assumes that the date is in the twentieth century. If the year is less than 50, Progress assumes that the date is in the twenty-first century.

> Table 4–7 shows examples of `-yy`.

> Table 4–7: Century setting and date format
> -yy | Year (as supplied in DATE format) | Result of year function
> --- | --- | ---
> 1900 | 50-99 | 1950-1999
> 00-49 | 1900-1949
> 1950 | 50-99 | 1950-1999
> 00-49 | 2000-2049
> 1980 | 80-99 | 1980-1999
> 00-79 | 2000-2079

> Notice that all two-digit year values expand into the 100-year period beginning with `-yy`.

> To test the effect of `-yy`, start Progress with a different `-yy` value and run the following procedure:

>     DEFINE VARIABLE ddate AS DATE.
>     DISPLAY "Enter date or Press F4 to end." WITH FRAME msg.
>     REPEAT:
>       SET ddate LABEL "Date" WITH SIDE-LABELS.
>       DISPLAY YEAR(ddate) FORMAT "9999" LABEL "=> Year"
>       WITH SIDE-LABELS.
>     END.

> If you use a hard-coded date containing a two-digit year in a `.p` file, Progress honors the `-yy` parameter and expands the two-digit year to a four-digit year during compilation. However, this may not match the runtime `-yy`. For this reason, Progress Software Corporation recommends that you use four digit years for hard-coded dates in programs. For example:

>     DEFINE VARIABLE hdate AS DATE INITIAL 01/01/2001.

> Note: When you dump or load any database, the `-yy` setting you load with must match the `-yy` setting that was used for dumping, unless you use the Four Digit Year Default (-yr4def) startup parameter for dumping.

> This startup parameter provides the same functionality as the `SESSION:YEAR-OFFSET` attribute.

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