I tried to package all the user defined functions as addin. Lots of user
defined functions are based on parameters from lookup tables. Therefore,
to prevent any modification to the lookup table, I'd like to put all the
related data in addin file and I assigned the range name for the lookup
data area. I don't know how to refer to the named range in the
user defined functions or the formula in worksheet.

For example, the parameters are inputted to the user defined function,
then the user defined function will find the data in addin file and
return the result.

In addition, Please give some suggestions how to protect the lookup data
in Excel VBA Programming.

Thanks