.. Functions ..
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Set/close filter

 With Alt+L ,you can set a filter to the actual data. When the filter is
 set, only the data fits the filter conditions, will appear. You close the
 filter with Alt+C , or by giving no response (blank) to filter conditions.

 For filter conditions, you can use also normal Clipper/dBase/Foxpro etc..
 syntax (.and., .or., .not., ! eof(), deleted()....)
    Examples:  .not. deleted()
                .not. eof()
                name="Meier" .and. lastname="Max" .and. number>0
                trim(name)="Mei" .or. dtoc(date)="01.01.92"

    Also changed values are allowed:
    Examples: str(number), val(sign), dtoc(date), substr(name)...


 Values blend:
   When blend-Mode (Alt+B) is ON, the contend of the actual field will
   appear on the screen.

 When the filter is ON, it is not possible to add new data with insert-key.

 - You get a choice of fields (for filter conditions) with Shift+F2 .