ref: 9b63280ae87d3215c083794705d44b9099610eb7
dir: /sys/lib/troff/font/devutf/charlib/sq/
/build_sq { pop size 2 div /side exch def currentpoint newpath moveto 0 side rlineto side 0 rlineto 0 side neg rlineto closepath font B eq {fill} {stroke} ifelse } def