YSLW - Year Sliding or Fixed Window

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# YSLW - Year Sliding or Fixed Window

This Natural profile parameter specifies the range of years covered by the "year sliding window" or "year fixed window".

Note
The sliding-window or "year fixed window" mechanism assumes a date with a 2-digit year to be within a "window" of 100 years. Within these 100 years, every 2-digit year setting is uniquely related to a specific century, so that there is no confusion about which century is meant.

Possible settings | Normal Setting | `0` | When you set the parameter to `0`, the current century is assumed. No sliding or fixed-window mechanism is used.
Sliding Window | `1 - 99` | By setting the parameter to a value between `1-99`, you determine when the 100-year range begins in the past. The `YSLW` setting is subtracted from the current year to determine the first year of the window range. See Example of a Sliding Window.
Fixed Window | `1582-2600` | By setting the parameter to a value between `1582-2600`, you determine the first year of a 100-year range. The upper boundary of the 100-year range is evaluated by adding `99` to the value specified. See Example of a Fixed Window.
Default setting | `0` | No sliding or fixed-window mechanism is used.
Dynamic specification | yes |
Specification within session | no |

The `YSLW` parameter is evaluated at runtime when an alphanumeric date setting with a 2-digit year component is moved into a date variable. This applies to date settings which are:

- used with the mathematical function `VAL`;

- used with the `IS(D)` option in a logical condition;

- read from the stack as input data;

- or entered in a map as input data.

See also the section Processing of Date Information in the Programming Guide.

## Examples of YSLW Parameter

### Example of a Sliding Window

If the current year is 2014 and you specify `YSLW=40`, the sliding window will cover the years 1974 to 2073. A 2-digit year setting `nn` from `74` to `99` is then interpreted accordingly as `19nn`, while a 2-digit year setting nn from `00` to `73` is interpreted as `20nn`.

See also the examples under Year Sliding Window - YSLW Parameter and Combinations of DFSTACK and YSLW in the Programming Guide.

### Example of a Fixed Window

If you specify `YSLW=1985`, the fixed window will cover the years 1985 to 2084. A 2-digit year setting `nn` from 85 to 99 is then interpreted accordingly as `19nn`, while a 2-digit year setting `nn` from `00` to `84` is interpreted as `20nn`.