HP 32SII - Manual (Page 165)

Simple Programming 12–3
File name 32sii-Manual-E-0424
Printed Date : 2003/4/24 Size : 17.7 x 25.2 cm
Program Boundaries (LBL and RTN)
If you want more than one program stored in program memory, then a
program needs a label to mark its beginning (such as

   ) and a
return to mark its end (such as 
 ! ).
Notice–that the line numbers acquire an  to match their label.
Program Labels
Programs and segments of programs (called routines) should start with a label.
To record a label, press:
z “ letter–key
The label is a single letter from A through Z. The letter keys are used as they
are for variables (as discussed in chapter 3). You cannot assign the same
label more than once (this causes the message
" !) ), but a
label can use the same letter that a variable uses.
It is possible to have one program (the top one) in memory without any label.
However, adjacent programs need a label between them to keep them
distinct.
Program Line Numbers
Line numbers are preceded by the letter for the label, such as 
 .
If one label's routine has more than 99 lines, then the line number appears
with a decimal point instead of the leftmost number, such as
)
 for line
101 in label A. For more than 199 lines, the line number uses a comma, such
as
8
 for line 201.
Program Returns
Programs and subroutines should end with a return instruction. The keystrokes
are:
{ ”
When a program finishes running, the last RTN instruction returns the
program pointer to
 ! , the top of program memory.