2.11BSD/src/share/learn/editor/L7.1a

#print
Although specifying lines by line number is
easy to understand, it is hard to do in a long
file.  You will therefore want to learn other
ways of addressing lines.  The 'current line'
is addressed with the symbol 
  .
so that it can be printed, for example with
  .p
just as you could print a line by "3p".
Try that in this file; the current line is
set to the last line of the current file.
Try ".p"; then "w", "q", and "ready" as usual.
Here's the full file -

#create Ref
:john quincy adams
#create file
george washington
john adams
thomas jefferson
james madison
james monroe
john quincy adams
#print file
#copyout
#pipe
ex +'set prompt noopt open' file
#user
#unpipe
#uncopyout
grep quincy .ocopy >X1
#cmp X1 Ref
#log
#next
7.1b 10