"XOX window" is a term used to describe a specific configuration of a sliding window.

Here's what it means:

• The term "XOX" refers to the arrangement of the window panels as viewed from the exterior.
• "X" represents an operable (sliding) sash or panel.
• "O" represents a fixed (non-operable) panel.

So, in an "XOX" sliding window, you have three panels: the left and right panels are operable (they can slide), and the center panel is fixed. This configuration is common in wider windows where you want ventilation on each side with a fixed central view.