Rebol []

  encode-url: func [
      {Converts string to a CGI argument string.}
      args [any-string!] "Starts at first argument word"
  ][
      replace/all args "%" "%25"
      replace/all args "+" "%2B"
      replace/all args "," "%2C"
      replace/all args ":" "%3A"
      replace/all args "<" "%3C"
      replace/all args ">" "%3E"
      replace/all args " " "%20"
      replace/all args "[" "%5B"
      replace/all args "]" "%5D"
      replace/all args "^^" "%5E"
      mold to-url args
  ]