the "addField" method

[mohamida]

in the documentation:it's said that

a field name different than the name of any subscribed field

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

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

or

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

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

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

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