Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 281)

Introduction to Programming
Chapter 10
10-7
The control sequentially executes blocks in a part program to conduct the
required machining operation.
Important: To make jumps, loops, or calculations within an executing
program or subprogram use the paramacro features as discussed in chapter
28. A part program has a:
beginning ---- setting up the control and the machine to perform the
operations wanted.
middle ---- performing the machining operations
end ---- returning the machine to a safe stop position, and preparing the
control for the next part program.
The blocks programmed vary for each section of the program. For an
example, consider the following simple program.
Example 10.2
Simple Part Program
G91G21;
G00X28.;
G33Z-46.E4.;
G00X5;
Z2.;
M02;
-beginning
-middle
-end
A complete part program may consist of a main program and several
subprograms. For more on subprograms, see section 10.3.