VAR(VAR1, ... , VAR N) - creates variables VAR1, ... VAR N if they don't exist. 

Initial value for each new created variable is empty string. If report variable exists, it is not changed in any way. When you use declared variable with UDF, you may need to init its value by your own code. 

Example: 

\scan(a), var(totsal), my_init_function(totsal)\ 

--------------- 

\scan(b), my_special_sum_function(b:field1,totsal)\ 

\b:number\ \b:field1\ 

\endscan\ 

total: \totsal\ 

\endscan\