Box drawing characters are widely used in text user interfaces to draw various frames and boxes. In graphical user interfaces these characters are useless, because it is much simpler to draw lines and rectangles directly with graphical APIs; besides, box drawing characters work only with fixed-width fonts.

Unicode includes 128 such characters:

In all MS-DOS codepages box drawing characters are present, but their number is limited to 40:

│┤╡╢╖╕╣║╗╝╜╛┐└┴┬├─┼╞╟╚╔╩╦╠═╬╧╨╤╥╙╘╒╓╫╪┘┌

or even to 22:

│┤╣║╗╝┐└┴┬├─┼╚╔╩╦╠═╬┘┌

And for UNIX programs, usually only 11 basic characters are available:

│┤┐└┴┬├─┼┘┌

or, on some terminals, they are not available at all, so they are replaced with such ASCII characters as '_', '|' and '+'.