From the Excel 2002 help file:

You can also use a reference style where both the rows and the columns on the worksheet are numbered. The R1C1 reference style is useful for computing row and column positions in macros. In the R1C1 style, Excel indicates the location of a cell with an "R" followed by a row number and a "C" followed by a column number.

Reference Meaning
R[-2]C A relative reference to the cell two rows up and in the same column
R[2]C[2] A relative reference to the cell two rows down and two columns to the right
R2C2 An absolute reference to the cell in the second row and in the second column
R[-1] A relative reference to the entire row above the active cell
R An absolute reference to the current row

When you record a macro, Excel records some commands by using the R1C1 reference style. For example, if you record a command such as clicking the AutoSum button to insert a formula that adds a range of cells, Excel records the formula by using R1C1 style, not A1 style, references.

To turn R1C1 reference style on or off
Click Options on the Tools menu, and then click the General tab.

Under Settings, select or clear the R1C1 reference style check box.