The Select to Channel command saves the selection as a channel. The channel can then be used as a channel selection mask. You can find more information about them in the Channel Dialog section.

You will find a simple example how to use this command in the introduction of Раздел 16, «Фильтры альфа в логотип». It shows how to convert a selection to an alpha channel so that you can apply an alpha to logo filter to this selection.