Excell stands for EXtended CELL and represents the cell editor in the grid.

The way the data will be stored|shown|edited in the grid is controlled by the column type. Each column type refers to the related excell object:
ro ⇒ eXcell_ro
ed ⇒ eXcell_ed
… While API allows to attach events and update settings to control some aspects of data rendering, the full control can be achieved only by customizing (or creating new one) excells.
In most cases it is enough to redefine some single method of excell to change the related behavior - the full list of excell methods is provided here.

Creating Read-Only Excells (formatters)

Creating Editable Excells