This function checks to see if its first argument is an error string. If the value isn't an error it is returned as-is, otherwise a replacement value is returned.
IfErrorString([Primary Value], [Error Replacement Value])
Primary Value is the value to check for an error.
Error Replacement Value is the value to use if the primary value is an error.
|IfErrorString(DWVariableName,"Please Enter a Valid Name")
|Will return Please Enter a Valid Name when the value coming from the variable Name is an error.