BDAY-param = BDAY-param-date / BDAY-param-text
BDAY-value = date-and-or-time / text
  ; Value and parameter MUST match.

BDAY-param-date = "VALUE=date-and-or-time"
BDAY-param-text = "VALUE=text" / language-param

BDAY-param =/ altid-param / calscale-param / any-param
  ; calscale-param can only be present when BDAY-value is
  ; date-and-or-time and actually contains a date or date-time.
