The interpreter maintains the basic mathematical operations: addition,
subtraction, multiplication and division with their priorities. So if
the user wants to add the values of two tags, the parse will look like
$$FIELD+FIELD.
Example:
$$phd#snapshot#day_val_d0_h12#TI301_63.PV + phd#snapshot# day_val_d0_h12#TI301_64.PV
Where TI301_63.PV and TI301_64.PV are the names of the tags, which values have to be added.
A field can be a constant number.
Example:
$$phd#snapshot#day_val_d1_h12#TI301_63.PV+ 152.34
This line will return as a result the sum of the values of the tag
TI301_63.PV and the number 152.34.
Using formulas in the template is also allowed but visual basic scripts are not.