By default, all variables with names beginning with I, J, K, L, M,
  or N are assumed to be integer variables.  Variables beginning with
  any other letter are assumed to be real variables.

  Names beginning with a dollar sign ($) are implicitly INTEGER.

  You can override the default data type implied in a name by
  specifying data type explicitly in either an IMPLICIT statement or
  a type declaration statement.

  Note:  You cannot change the implicit type of a name beginning with
  a dollar sign in an IMPLICIT statement.