How to built an SPF record that is split in substrings?

Look at the SPF record of tdlc.com:

tdlc.com. 3600 IN TXT (
  "v=spf1"
  "a"
  "mx"
  "ptr"
  "a:smtp.meridiancg.com"
  "a:email.meridiancg.com"
  "a:smtp-high.meridiancg.com"
  "ip4:69.7.105.0/27"
  "208.20.231.0/24"
  "-all"
  )

Is that valid or invalid? How show SPF concatenate the strings? Should it
insert spaces? Should it insert a space only if the length of string is not
255?

Roger