Separated Block Sextant-245

It is a three-cell tile in a six-cell picture grid. “Sextant” here means a mosaic divided into six cells, arranged as two columns and three rows. The digits 2, 4, and 5 name the filled cells: upper right, middle right, and lower left. Other tiles can join it to make a larger block picture.

Why does this sextant have gaps?

The gaps preserve the separated teletext display style. The first edition of the UK broadcast teletext specification appeared in October 1974; a joint 1976 edition describes six-cell mosaics in both contiguous form, where cells touch, and separated form, with small gaps. Teletext sent text and simple graphics over television broadcasts, using unused lines in the signal.

These mosaics let systems make small pictures from character cells. In teletext, separation was originally selected as a display mode. In 2021, a Unicode proposal recorded requests for separate characters so teletext emulators and software with their own private character assignments could preserve these patterns as text.