Hi satch,

Is present and Is blank are used in conditional formatting.
say, for example textbox ,data sourse is field1.
by making use of conditional formatting we can use Ispresent and Isblank
like this
Field1 is present means ,we are checking whether the value is present in the
field.
Field1 Isblank means, we are checking whether the field is blank.

Is Present lets you check whether the node actually exists in the XML DOM.
Is Blank checks whether the value of the node (if present) is blank.