Plan 9 from Bell Labs’s /usr/web/sources/contrib/steve/root/sys/src/cmd/tex/web2c/mp/mp-plumb.ch
@x [27.1] if name>max_spec_src then begin print_nl("l."); print_int(true_line); end @y if name>max_spec_src then begin print_nl(":"); print_int(true_line); end @z