They're often termed as 'French Casements' or 'Inswing French Casements.' At least I know that's the terminology that Andersen, Marvin, Pella, etc. use.
In my experience, they are not always offered in every product line. They are really handy for situations with true shutters (as Christiaan mentioned) or in my case, the desire to have a combination of casement and double-hung windows with the insect screens consistently located on the exterior.