ispell-dictionary-keyword is a variable defined in `ispell.el'.
Its value is
"Local IspellDict: "
This variable may be risky if used as a file-local variable.
Documentation:
The keyword for a local dictionary to use.
The keyword must be followed by a valid dictionary name, defined in
`ispell-local-dictionary-alist' or `ispell-dictionary-alist'.
When multiple occurrences exist, the last keyword
definition is used.