chunk 1: Always format .Pa the same way, as requested by jmc@ (local change).
chunks 2-3: Do not misinterpret .Lk args as macros (committed upstream, too).

Index: tmac/doc.tmac-u
--- tmac/doc.tmac-u.orig
+++ tmac/doc.tmac-u
@@ -3761,8 +3761,6 @@
 .
 .        if \n[doc-in-files-section] \{\
 .          ds doc-saved-Pa-font "\*[doc-Pa-font]
-.          if n \
-.            ds doc-Pa-font "\*[doc-No-font]
 .        \}
 .
 .        ie (\n[doc-type1] == 1) \
@@ -6485,10 +6483,11 @@
 .  if (\n[doc-arg-ptr] <= \n[doc-lasttext-Lk]) \{\
 .    nop \*[doc-Em-font]\c
 .    while (\n[doc-arg-ptr] < \n[doc-lasttext-Lk]) \{\
-.      nop \*[doc-arg\n[doc-arg-ptr]]
+.      nop \&\*[doc-arg\n[doc-arg-ptr]]
 .      nr doc-arg-ptr +1
 .    \}
-.    nop \*[doc-arg\n[doc-arg-ptr]]\f[\n[doc-curr-font]]\s[\n[doc-curr-size]u]:
+.    nop \&\*[doc-arg\n[doc-arg-ptr]]\c
+.    nop \f[\n[doc-curr-font]]\s[\n[doc-curr-size]u]:
 .    nr doc-arg-ptr +1
 .  \}
 .
@@ -6498,7 +6497,7 @@
 .
 .  \" Print the delimiters, if any.
 .  while (\n[doc-arg-ptr] <= \n[doc-arg-limit]) \{\
-.    nop \*[doc-arg\n[doc-arg-ptr]]\c
+.    nop \&\*[doc-arg\n[doc-arg-ptr]]\c
 .    nr doc-arg-ptr +1
 .  \}
 .  nop \&