RCML program consists of two key sections: the section of inclusions and the section of functions.

Example of RCML program:

// Section of inclusions

// Section of functions
function sum(a, b) {
	c = a + b;
	return c;
function main() {
	s = sum(1, 2);
	echo(“sum = ”,s,”\n”);

Other RCML program files with the text that should be included in this program may be specified in the section of inclusions. It can be sets of any functions, additional libraries, etc. However, the section of inclusions may be empty as well.

The section of functions starts after the first mention of function keyword. Main program code is specified in the section of functions, which consists of functions. 

By analogy with C and C++ programming languages, execution begins with a function named main, which must be present. This statement refers to executable RCML programs (not libraries). The difference between the library and the executable program will be described later.