the "addField" method

in the documentation:it's said that

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a field name different than the name of any subscribed field

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For example, in the stocklist page, there's:

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updateInfo.addField("#trend_color",redColor,true);

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or

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updateInfo.addField("#fade","ON",true);

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but there isin't a table row with a "field" named "#trend_color" or "#fade" like for the "#arrow " field !!

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<span source="lightstreamer" table="main" item="'+i+'" field="#arrow">

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what the method "addField" is used for ???

In the reported cases, we use extra fields just as "decorators".

In fact, we want to format some fields in a way that depends on the previous value of the field.
However, in the onChangingValues callback (the place where formatting instructions can be given to the VisualTable), the previous values of the updated fields are not available.
On the other hand, they are available in the onItemUpdate callback.

By using extra fields, we can store the needed information (for instance, the price trend) in the current update within onItemUpdate and retrieve it in the subsequent call to the formatting callback onChangingValues.

thank you :D