Later, when the research group acquired a photo-typesetter, nroff was enhanced to deal with the newly acquired capabilities, and thus troff was born. In the early 1980's, after the death of Mr. Osanna, Brian Kernighan took over troff , cleaned it up and enhanced it. The troff language is now frozen. It will not evolve further. Typically, commands are on separate lines by themselves.
Special tricks have to be used to get troff to treat a line that begins with a dot as real text.
There are a large number of commands in troff . This means putting as many words of input text on one output line as possible. This means padding lines with blanks so that the margins on both sides are even. Book and magazine text is typically both filled and adjusted. Printed text is often in multiple fonts.