**label**- A descriptive text in a cell that is not used for any calculations.
**expression**- A string in a cell which evaluates to a (floating point)
numeric result. The
simplest expression is a number; more complicated expressions
can be entered in Scheme syntax.
The Scheme used in Siag has a few extensions to make it more useful in a spreadsheet. These new functions have been added:

**(row)**Returns the row number of the cell which is being computed.**(col)**Returns the column number of the cell which is being computed.**(get-cell***row col***)**Returns the contents of the cell with the given coordinates.**(sum***start end***)**Returns the sum of all the cells in the rectangle between*start*and*end*.

**grid**- The area where labels and expressions are displayed.
**colnum**- The grey area where column numbers are displayed.
**rownum**- The grey area where row numbers are displayed.
**mark**- The "other" standard position in the document, which is used for commands which need two coordinates.
**point**or**current cell**- The cell where labels and expressions are entered. The current cell can be moved using arrow keys, the mouse and other methods.
**block**- The block is a rectangular area which is displayed in inverse. It is used for commands which operate on a whole range of cells.

Ulric Eriksson - January 1997 - ulric@siag.nu