Page of GC20-1807-7 As Updated April 1, 1981 by TNL GN25-0829
7. When describing an area of storage in mainline code, a copy file,
or a macro, DSECT is issued containing DS instructions.
8. Meaningful names are used instead of self-defining terms: for
example, 5,X'02',C'I' to represent a quantity (absolute address,
displacement, length, register, etc.). All labels, displacements,
and values are symbolic. All bits should be symbolic and defined
by an equate (EOU) listing. For example: VMSTATUS EOU X'02' To set a bit, use: 01 BYTE, BIT
where BYTE = name of field, BIT is an EOU symbol.
To reset a bit, use:
NI BYTE,255-BIT To set multiple bits, use: 01 BYTE,BIT1+BIT2 etc.
All registers are referred to as: RO, R1, ••• , R15.
All lengths of fields or control blocks are symbolic, that is,
length of VMBLOK is: VMBLOKSZ EQU *-VMBLOK 9. Avoid absolute relative addressing in branches and data references,
(that is, location counter value (*) or symbolic label plus or
minus a self-defining term used to form a displacement). 10. When usinq a sinqle operation to reference multiple values, specify
each value referenced, for example: LM R2,R4,CONT SET R2=CON1 SET R3=CON2 SET R4=CON3 CON1 CON2 CON3 DC F'1'
DC F'2'
DC F
I
3
1 11. Do not use PRINT NOGEN or PRINT OFF in source code.
212 IBM VM/370 System programmer's Guide

12. MODULE NAMES: Control Section Names and External References are as follows:
Control Section or Module Name The first three letters of the module name are the
component code. Example: DMK The next three letters of the module name identify the module and
must be unique.
Example: DSP This three-letter, unique module identifier is the label of the
TITLE card.
Each entry point or external reference must be prefixed by the six
letter unique identifier of the module.
Example: DMKDSPCH 13. TITLE CARD: DSP TITLE 'DMKDSP VM/370 DISPATCHER VERSION v LEVEL l'
14. PTF Card
Example: CP/CMS: PUNCH 'xxxxxxxx APPLIED' xxxxxxxx is the APAR number response
15. ERROR MESSAGES: There should be no insertions
and the length of the message
If insertions must be made,
several DC statements, and
individually labeled.
into the message at execution time
should be resolved by the assembler.
the message must be assembled as
the insert positions must be
16. For all RX instructions use a comma (,) to specify the base
register when indexing is not being used, that is:
L R2,AB(,R4)
17. To determine whether you are executing in a virtual machine or in a
real machine, issue the Store Processor ID (STIDP) instruction. If STIDP is issued from a virtual machine, the version number (the
first byte of the CPUID field) returned will be X'FF'. Part 2. Control Program (CP) 213