Implicit Typing Rules

By default, all variables, named constants, and functions with names beginning with I, J, K, L, M, or N are assumed to be of default integer type. Variables, named constants, and functions with names beginning with any other letter are assumed to be of default real type. For example:

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

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