ASSL. How does <DataItem><Format> work?

Hi Gurus,
I have question related to the <Format>

What it designed for? How should it work?

<Attribute>
<ID>Datum Lieferung</ID>
<Name>DatumLieferung</Name>
<KeyColumns>
<KeyColumn>
<DataType>Date</DataType>
<Format>yyyy.mm.dd</Format>
<Source xsi:type="ColumnBinding">
<TableID>AuftragOffen</TableID>
<ColumnID>DatumLieferung</ColumnID>
</Source>
</KeyColumn>
</KeyColumns>
<Translations>
<Translation>
<Language>1031</Language>
<Caption>Datum Lieferung</Caption>
</Translation>
</Translations>
<OrderBy>Key</OrderBy>
</Attribute>

<Attribute>
<ID>Datum Lieferung</ID>
<Name>DatumLieferung</Name>
<KeyColumns>
<KeyColumn>
<DataType>Date</DataType>
<Source xsi:type="ColumnBinding">
<TableID>AuftragOffen</TableID>
<ColumnID>DatumLieferung</ColumnID>
</Source>
</KeyColumn>
</KeyColumns>
<NameColumn>
<DataType>WChar</DataType>
<Format>dd.mm.yyyy</Format>
<Source xsi:type="ColumnBinding">
<TableID>AuftragOffen</TableID>
<ColumnID>DatumLieferscheinDruck</ColumnID>
</Source>
</NameColumn>
<Translations>
<Translation>
<Language>1031</Language>
<Caption>Datum Lieferung</Caption>
</Translation>
</Translations>
<OrderBy>Key</OrderBy>
</Attribute>
I have tested it in various ways but it seems to be ignored by AS.

Newertheless in BOL is written

Allowed values for the Format element are Microsoft Office Excel formats, and the strings TrimRight, TrimLeft, TrimAll, and TrimNone. For trimming, TrimRight is the default.

The value of this element is limited to one of the strings in the following table.

Value	Description
Any Excel format string	Data is formatted according to the specified named or custom format string. Any format string that Excel supports can be supplied.

Can anybody help me?

Is this a bug?

Where you able to find the answer to this? I am looking for the same thing.