property Items.CellValueFormat([Item as Variant], [ColIndex as Variant]) as ValueFormatEnum
Specifies how the cell's caption is displayed.

TypeDescription
Item as Variant A long expression that indicates the item's handle
ColIndex as Variant A long expression that indicates the column's index, or a string expression that indicates the column's caption or 
column's key.
ValueFormatEnum A long expression that defines the way how the cell's value is displayed

The component supports built-in HTML format. That means that you can use HTML tags when displays the cell's value . By default, the CellValueFormat property is exText. If the CellValueFormat is exText, the cell displays the CellValue property like it is. If the CellValueFormat is exHTML, the cell displays the CellValue property using the HTML tags specified in the ValueFormatEnum type. Use the Def property to specify whether all cells in the column display HTML format. Use the CellVAlignment property to align vertically a cell.

The CellValue property of the cell is being shown as:

In other words, all cells applies the format of the FormatColumn property, excepts the cells with the FormatCell property being set. If the cell belongs to a column with the FireFormatColumn property on True, the Value parameter of the FormatColumn event shows the newly caption for the cell to be shown