[A-Z0-9 ,"&-']

##</code><code>##

  /^[A-Z0-9 ,"&-']{4,16}$/

##</code><code>##

  # Please excuse the long line ;)
  /^[A-Z0-9 ,"&-'][A-Z0-9 ,"&-'][A-Z0-9 ,"&-'][A-Z0-9 ,"&-'][A-Z0-9 ,"&-']?[A-Z0-9 ,"&-']? ... repeat total 12 times ... [A-Z0-9 ,"&-']?$/

##</code><code>##

  # The set for the characters gets changed :
  [A-Za-z0-9 ,"&-']

  # and the RE then looks like this :
  /^[A-Za-z0-9 ,"&-']{4,16}$/

  # and we can modify the RE, so that A-Z also matches
  # a-z with the "i"-modifyer :
  /^[A-Z0-9 ,"&-']{4,16}$/i

  # or equivalent

  /^[a-z0-9 ,"&-']{4,16}$/i