Syntax - @IF(Expression,TruePart,FalsePart)
Parameters :
Expression - Any logical expression (see Filters and Formula Operators).
TruePart - Any operator, function, field or literal text.
FalsePart - Any operator, function, field or literal text.
Action - If Expression = 0 (or blank), returns the FalsePart. Otherwise, returns the TruePart.
Example - @IF([INV:Price]>0,[INV:Price],Needs Price)
Result - If the Price is greater than 0, prints the Price. If the Price is 0 (or less), prints the message, "Needs Price".
See:
Filters and Formula Functions - All
Filters and Formula Operators
Filters - Transaction Types