.. July 4, 1983 demo of nesting of strings and macros:
.. try typing the command:
.."A>roff4 nest -i -m ) "
..
.pl 30 ;saving paper
.ds .1st.first.
.ds .2nd.second.
.ds .all.\1st\ \2nd\.
.ds .ALL.\\1st\\ \\2nd\\.
=\all\
=\ALL\
=\all\
=\ALL\
=
.dm xx
.yy
.yy
.em
.dm yy
.zz
.zz
.em
.dm zz
hello, there!

.em
.xx	;supposed to form .zz four times
.xx