A special character may be an operator or part of a constant or have some other special meaning. The interpretation is implied by context. Except for assignment and statement function statements, each statement begins with a keyword. In this standard, the keyword or keywords that begin the statement are used to identify that statement. 2.3.1 Classes of Statements.
Executable statements specify actions.
2.4 Program Units and Procedures A program unit consists of a sequence of statements and optional comment lines. A program unit is either a main program or a subprogram. Function subprograms and subroutine subprograms are called procedure subprograms. Subroutines and external functions are called external procedures. 2.4.2 Executable Program.