空心方框字体可以通过使用Unicode字符来实现。以下是一些常见的空心方框字符：
□ U+25A1 WHITE SQUARE
▢ U+25A2 WHITE SQUARE WITH ROUNDED CORNERS
▣ U+25A3 WHITE SQUARE CONTAINING BLACK SMALL SQUARE
▤ U+25A4 SQUARE WITH HORIZONTAL FILL
▥ U+25A5 SQUARE WITH VERTICAL FILL
▦ U+25A6 SQUARE WITH ORTHOGONAL CROSSHATCH FILL
▧ U+25A7 SQUARE WITH DIAGONAL CROSSHATCH FILL
▨ U+25A8 SQUARE WITH UPPER LEFT TO LOWER RIGHT FILL
▩ U+25A9 SQUARE WITH UPPER RIGHT TO LOWER LEFT FILL
▭ U+25AD WHITE RECTANGLE
▮ U+25AE BLACK VERTICAL RECTANGLE
▯ U+25AF WHITE VERTICAL RECTANGLE
▱ U+25B1 WHITE PARALLELOGRAM
△ U+25B3 WHITE UP-POINTING TRIANGLE
▵ U+25B5 WHITE UP-POINTING SMALL TRIANGLE
▹ U+25B9 WHITE RIGHT-POINTING SMALL TRIANGLE
▼ U+25BC BLACK DOWN-POINTING TRIANGLE
◊ U+25CA LOZENGE
