Hi Jean
Formula Options Displays differently in the formula bar.
Calc A1 formula in cell A1= 2*SUM(B1:B4)
Excel A1 formula in cell A1 = 2*SUM(B1:B4)
Excel R1C1 formula in cell R1C1 =2*SUM(RC[1]:R[3]C[1]) R=Row C=Column obviously
In this simple example the difference between the first 2 are not obvious but the separators are different in some versions Excel and Calc when typed from the keyboard. The separators choices seem to override this in the examples I tried and the above.
I have never used the the Excel R1C1 type.
I would say that the explanation has been put in the "too hard" file. I cannot think of one that covers the first 2. The Excel R1C1 formula the column letters are changed to be numbers as well as the rows in the top 2. The formula shows where the answer is going.
As for Compatibility I do not know.
- Ian