& &
 
  Command: &<attribute> <object>[=<value>]
  Synonym: @set <object> = <attribute>:[<value>]
 
  Sets the attribute named <attribute> on <object> to <value>.  If
  <attribute> is not a predefined attribute (like ofail or va), then it is
  created.  Attributes so created are called user-named attributes.
  Attribute names may only contain letters, numbers, and the characters
  < -_.@#$^&*~?=+| >, and must start with a letter.  The names of user-named
  attributes may not be abbreviated (an attempt to get the value of the
  attribute will fail, and an attempt to set will create a new attribute).
  The & command may be used to set predefined attributes (in this instance,
  '&<attr> <object>=<value>' is equivalent to '@<attr> <object>=<value>').
 
  See also: @set