Leaders

[Peter Schaffter]

I'm having trouble making sense of leader behaviour.

cat <<EOF | groff -Kutf8 -k -Tutf8
.pl 3v
.ta \n[.l]u
The château into which my valet had ventured to make forcible
entrance, rather than permit me, in my deparately wounded condition,
to pass a night in the open air\a
EOF
  => The château into which my valet had ventured to make forcible en‐
     trance,  rather  than  permit me, in my deparately wounded condi‐
     tion, to pass a night in the open air

Notice that \a is not interpolating leaders.  Replacing \a with 

(ctrl-va) interpolates the leaders, but the output is wonky.

cat <<EOF | groff -Kutf8 -k -Tutf8
.pl 3v
.ta \n[.l]u
The château into which my valet had ventured to make forcible
entrance, rather than permit me, in my deparately wounded condition,
to pass a night in the open air

EOF
  => The château into which my valet had ventured to make forcible en‐
     trance,  rather  than  permit me, in my deparately wounded condi‐
     tion,     to     pass     a      night      in      the      open
     air..................................

Leaving aside the wonky output for a moment, if the text is wrapped
in a macro, \a succeeds.

cat <<EOF | groff -Kutf8 -k -Tutf8
.pl 3v
.ta \n[.l]u
.de foo
The château into which my valet had ventured to make forcible
entrance, rather than permit me, in my deparately wounded condition,
to pass a night in the open air\a
..
\*[foo]
EOF
  => The château into which my valet had ventured to make forcible en‐
     trance,  rather  than  permit me, in my deparately wounded condi‐
     tion,     to     pass     a      night      in      the      open
     air..................................

Question 1:
Is \a only interpreted in copy mode as this would suggest?

Question 2:
What is causing the erroneous justification of the third line?
There's more than enough room for "air" and some leader.

Question 3:
Why do the leaders not respect .ta \n[.l]u?

-- 
Peter Schaffter
https://www.schaffter.ca