A computed field or cell displays the result of an arithmetic formula that may include operators, variables and constants. By default, the ComputedField property is empty. If the the ComputedField property is empty, the property have no effect. If the ComputedField property is not empty, all cells in the column, that have the CellValueFormat property on exText, uses the same formula to display their content. For instance, you can use the CellValueFormat property on exHTML, for cells in the column, that need to display other things than column's formula, or you can use the CellValueFormat property on exComputedField, to change the formula for a particular cell. Use the FormatColumn property to format the column.

Use the CellValueFormat property to change the type for a particular cell. Use the CellValue property to specify the cell's content. For instance, if the CellValueFormat property is exComputedField, the Caption property indicates the formula to compute the cell's content. 

The Def(exCellValueFormat) property is changed to exComputedField, each time the ComputeField property is changed to a not empty value. If the ComputedField property is set to an empty string, the Def(exCellValueFormat) property is set to exText. Call the Refresh method to force refreshing the control.

The expression may be a combination of variables, constants, strings, dates and operators.  A string is delimited by ", ` or ' characters, and inside they can have the starting character preceded by \ character, ie "\"This is a quote\"". A date is delimited by # character, ie #1/31/2001 10:00# means the January 31th, 2001, 10:00 AM.

Samples:

1. "1", the cell displays 1
2. "%0 + %1", the cell displays the sum between cells in the first and second columns.
3. "%0 + %1 - %2", the cell displays the sum between cells in the first and second columns minus the third column.
4. "(%0 + %1)*0.19", the cell displays the sum between cells in the first and second columns multiplied with 0.19.
5. "(%0 + %1 + %2)/3", the cell displays the arithmetic average for the first three columns.
6. "%0 + %1 < %2 + %3", displays 1 if the sum between cells in the first  two columns is less than the sum of third and forth columns.
7. "proper(%0)'" formats the cells by capitalizing first letter in each word
8. "currency(%1)'" displays the second column as currency using the format in the control panel for money
9. "len(%0) ? currency(dbl(%0)) : ''" displays the currency only for not empty/blank cells.
10. "int(date(%1)-date(%2)) + 'D ' + round(24*(date(%1)-date(%2) - floor(date(%1)-date(%2)))) + 'H''" displays interval between two dates in days and hours, as xD yH
11. "2:=((1:=int(0:= date(%1)-date(%0))) = 0 ? '' : str(=:1) + ' day(s)') + ( 3:=round(24*(=:0-floor(=:0))) ? (len(=:2) ? ' and ' : '') + =:3 + ' hour(s)' : '' )" displays the interval between two dates, as x day(s) [and y hour(s)], where the x indicates the number of days, and y the number of hours. The hour part is missing, if 0 hours is displayed, or nothing is displayed if dates are identical.

The expression supports cell's identifiers as follows:

• %0, %1, %2, ...{any} specifies the value of the cell in the column with the index 0, 1 2, ... The CellCaption property defines the cell's value. For example, "%0 format ``" formats the value in the cell at index 0 using the current regional settings, while "int(%1)" converts the value in the cell at index 1 to an integer.
• %C0, %C1, %C2, ...{string} specifies the caption of the cell, or the string the cell displays in the column with the index 0, 1 2, ... The CellCaption property gets the cell's formatted caption. The cell's displayed string may differ from its actual value. For example, if a cell displays HTML content, %0 returns the HTML format including the tags, while %C0 returns the cell's content as a plain string without HTML tags. For instance, "upper(%C1)" converts the caption of the cell at index 1 to uppercase, while "%C0 left 2" returns the leftmost two characters of the caption in the cell at index 0.
• %CD0, %CD1, %CD2, ...{any} specifies the cell's extra data in the column with the index 0, 1 2, ... The CellData property associates any extra/user data to a cell. For example, "%CD0 = your user data" specifies all cells in the column with index 0 whose CellData property is equal to your user data.
• %CS0, %CS1, %CS2, ...{number} specifies the cell's state in the column with the index 0, 1 2, ... The CellState property defines the state of a cell, indicating whether it is checked or unchecked. For example, "%CS0" identifies all checked items in the column with index 0, while "not %CS1" identifies all unchecked items in the column with index 1.
• %CC0, %CC1, %CC2, ... {number} retrieve the number of child items (this keyword consistently returns identical results for all cells since it pertains to the item that hosts each cell). The ChildCount property returns the number of child items. For example, "%CC0" identifies all parent items, while "%CC0 = 0" identifies all leaf items.
• %CX0, %CX1, %CX2, ... {boolean} returns true if the item hosting the cell is expanded, or false if it is collapsed (this keyword consistently returns identical results for all cells since it pertains to the item that hosts each cell). The ExpandItem property specifically indicates whether the item is expanded or collapsed. For example, "%CX0" refers to all expanded items, while "not %CX0" identifies all collapsed items

This property/method supports predefined constants and operators/functions as described here.