# set-date-window command

The set-date-window command allows specifying
the rollover point on your system.

## Syntax

```
 set-date-window {n} {(options)}
```

## Parameter(s)

| n | Two-digit number specifying the rollover point (year). If a non-numeric parameter is specified, an error message is returned. If no parameter is specified, the currently set rollover point is returned. |
| --- | --- |
| options | The following options are supported: |
| c | Defines the century window to be used when converting a 2 digit year to 4 digits.Note: The valid values for the century setting are only 19 (20th century) or 20 (21st century) with the 20th century window as the default setting. |
| i | Suppress the output for this command. |
| x | Indicates that the value specified in n is expressed in hexadecimal format. |

## Description

The rollover point determines
the numeric cutoff for which century (20th or 21st) is being referred
to when representing the year in 2-digit format within a program.
For example, if the rollover point is set to 30 (the default), specifying
a 2-digit representation of the year between 00 and 29 means you are
referring to the years 2000 - 2029. Conversely, specifying a 2-digit
representation of the year between 30 and 99 means you are referring
to the years 1930 - 1999.

 In addition to set the year window, you can also set the century window setting by using the
 `(c` option.

| Century window | = Year window |
| --- | --- | --- |
| set-date-window 19 (c | 20xx (21st century) | 19xx (20th century) |
| set-dete-window 20 (c | 21xx (22nd century) | 20xx (21st century) |

## Examples

**Example 1**

This example illustrates displaying the currently set rollover point. In this case, the default
 rollover point (30) is returned (as in, 01/01/1930).

```
>set-date-window
 Current Date Window:30
```

 **Example 2**

This example illustrates setting the rollover point to 60 (as in, 01/01/1960).

```
>set-date-window 60
 Current Date Window:60
```

 **Example 3**: Set year window to 20th century

```
:set-date-window 19 (c
Current Century Window: 19
:set-date-window
Current Year Window: 30
:date 11/11/33
November 11, 1933; Saturday internal: -12468 julian: 315
:date 11/11/28
November 11, 2028; Saturday internal: 22231 julian: 316
```

 **Example 4**: Set year window to 21st century

```
:set-date-window 20 (c
Current Century Window: 20
:set-date-window
Current Year Window: 30
:date 11/11/33
November 11, 2033; Friday internal: 24057 julian: 315
:date 11/11/28
November 11, 2128; Thursday internal: 58755 julian: 316
```

---
Source: https://d3codex.com/tcl/set-date-window-command/ - part of the D3Codex reference.