+- .ad (adjust margins)
+ .ad l -- adjust left margin only (flush left)
+ .ad r -- adjust right margin only (flush right)
+ .ad c -- center text on line
+ .ad b -- adjust both margins (alias: .ad n)
+ .na -- temporarily disable adjustment without changing the mode
+ .ad -- re-enable adjustment without changing the mode
+ Adjustment mode is ignored while in no-fill mode (.nf).
+
+- .fc (field control)
+ found by naddy@ in xloadimage(1)
+
+- .nr third argument (auto-increment step size, requires \n+)
+ found by bentley@ in sbcl(1) Mon, 9 Dec 2013 18:36:57 -0700
+
+- .ns (no-space mode) occurs in xine-config(1)
+ reported by brad@ Sat, 15 Jan 2011 15:45:23 -0500
+
+- .ta (tab settings) occurs in ircbug(1) and probably gnats(1)
+ reported by brad@ Sat, 15 Jan 2011 15:50:51 -0500
+ also Tcl_NewStringObj(3) via wiz@ Wed, 5 Mar 2014 22:27:43 +0100
+
+- .ti (temporary indent)
+ found by naddy@ in xloadimage(1)
+ found by bentley@ in nmh(1) Mon, 23 Apr 2012 13:38:28 -0600
+
+- .while and .shift
+ found by jca@ in ratpoison(1) Sun, 30 Jun 2013 12:01:09 +0200