Docs typo, :- vs -

[Alfred Agrell]

Hello

https://git.savannah.gnu.org/cgit/bash.git/tree/doc/bash.info#n1842

'${PARAMETER:-WORD}'
     If PARAMETER is unset or null, the expansion of WORD is
     substituted.  Otherwise, the value of PARAMETER is substituted.

          $ v=123
          $ echo ${v-unset}
          123

The heading says :-, but the example just says -. Which one is intended? 
Or is it supposed to say that both are equivalent?

-- Alfred Agrell