length and record length equal to 80 bytes. Figure 9 shows t h e f o r m a t o f t h e v o l u m e l a b e l .
H E A D E B L A B E L 1 A N D T R A I L E R L A B E L 1 F O R M A T The first header and trailer labels identify the data contained on tape. These labels are written for the exclusive use of the s y s t e m . T h e y a r e w r i t t e n in E B C D I C f o r m a t w i t h a block length and record length equal to 80 bytes. Figure l0 shows t h e f o r m a t o f t h e f i r s t I B M standard h e a d e r a n d tr a i l e r la b e l s .
Displ
L n g in
bytes
Name
lDescription DisplL n g in
bytes N a m e Description
2 F 6 E x p i r a t i o n ' I h i s
f i e l d i n d i c a t e s t h e 0 0 3 L a b e l T h i s f i e l d i d e n t i f i e s t h e
,year and day of the year identifier type of label:
' r y h e n t h e f i l e m a y b e p u r g - H D R H e a d e r la b e l -r : d . T h e f o -r m a t o f t h i s E O F - E n d - o f - f i l e t r a i l e r
f i e l d i s i d e n t i c a l to t h e l a b e l .
rsreation date field. EOV - End-of-volume
t r a i l e r l a b e l ( f o r
35 1 Security This field indicates whether all but the final
o r n o t a d d i t i o n a l q u a l i f i c a - v o l u m e o f a m u l t i
-t i o n s m u s -t b e s u p p l i e d in v o l u m e f i l e ) '
order to access the file.
This field is set to zero on 03 1 Label Indicates the sequence of
S y s t e m / 3 ta p e s a n d i s n o t n u m b e r t h e l a b e l ' T h i s p o s i t i o n
verif ied by System/3. contains a 2 'f or System/3
taPes.
3 6 6 B l o c k T h i s i s a n u m e r i c f i e l d
count (000000-999999) indicat- 04 1 Record/ Indicates the record/block
i n g t h e n u m b e r o f b l o c k s b l o c k f o r m a t o f t h e f i l e :
between the last label of format V - Variable length
rec-t h e h e a d e r la b e l g r o u p a n d o r d s i n v a r i a b l e
t h e f i r s t t r a i l e r l a b e l . T h e l e n g t h b l o c k s '
c o u n t i s r e c o r d e d in t h e F - F i x e d - l e n g t h r e c o r d s t r a i l e r l a b e l o n l y ( E O F 1 o r i n f i x e d l e n g t h b l o c k s '
E O V I ) . T h e s e c h a r a c t e r s D - V a r i a b l e le n g t h
are recorded as zeros in the ASCII records'
h e a d e r la b e l .
0 5 5 B l o c k T h i s f i e l d i n d i c a t e s t h e 3 C 1 3 S y s t e m T h i s f i e l d c o n t a i n s l e n g t h f o l l o w i n g l e n g t h a t t r i b u t e s :
c o d e ' I B M 6 S y S T E M 6 1 " V - M a x i m u m b l o c k
length
(00009-49 7 Reserved This field is not used by 327671'
S y s t e m / 3 . F - C o n s t a n t b l o c k
l e n g t h ( 0 0 0 1 8
-Figure 1O (Part 3 of 31. IBM Standard for Tape Header Label 1 and 327671'
Trailer Label 1
N o t e : T h e m i n i m u m P h Y s -ical record length for mag-H E A D E R L A B E L 2 A N D T R A I L E R L A B E L 2 F O R M A T n e t i c t a p e s is 1 8 ; t h e r e f o r e '
i f t h e b l o c k l e n g t h i s t o T h e s e c o n d h e a d e r a n d t r a i l e r l a b e l s p r o v i d e a d d i t i o n a l e q u a l th e p h y s i c a l re c o r d i n f o r m a t i o n a b o u t t h e f i l e . T h e s e la b e l s a r e c h e c k e d b y l e n g t h , i8 s h o u l d b e u s e d
System/3 if they are present for input files and are created as the minimum in place of
for output files. However, System/3 will accept a file with- those given above.
o u t t h e s e c o n d h e a d e r o r t r a i l e r la b e l . T h e l a b e l s a r e w r i t t e n
i n E B C D | C f o r m a t w i t h a b l o c k l e n g t h a n d r e c o r d l e n g t h F i g u r e l l ( P a r t 1 o f 2 l . l B M s t a n d a r d f o r T a p e H e a d e r L a b e l 2 a n d
equal to 80 bytes. Figure 1 1 shows the format of the second Trailer Label 2
I B M s t a n d a r d h e a d e r a n d t r a i l e r l a b e l s .
A p p e n d i x A . T a p e l - a b e l F o r m a t s 2 9
4 1 Reserved
F i g u r e 1 1 lPafizol 2l.
This field indicates the following length attributes:
V - Maximum record length (0000b-327671.
F - Constant record length (00018-327671.
This field is not used by System/3.
This field indicates the tape recording technique used to create the file:
C6* Data conversion required.
E 6 - E v e n p a r i t y . T U - B C D to E B C D I C
translation required.
E T - E v e n p a r i t y a n d BCD t o E B C D I C t r a n s l a -tion required.
bb - Odd parity-no trans-l a t i o n re q u i r e d ( 9 -t r a c k ) .
This f ield is not used by System/3.
This field indicates one of the following record attri butes:
B - Records are blocked a n d n o t s p a n n e d . S - Records are spanned
a n d n o t b l o c k e d . B - Records are blocked
a n d s p a n n e d . 6 - Records are not
blocked and not s p a n n e d . This field is not used by System/3.
l 9
Record length
Reserved
Tape recording technique
Reserved
Record attributes
22
24
26
2 7
IBM Standard for Tape Header Label 2 and Trailer Label 2
30
A N S I . A m e r i c a n N a t i o n a l S t a n d a r d s I n s t i t u t e .
ASCll. American National Stan<lard Code for Information I nterchange.
bpi. Bits per inch per row (track) or the bytes per inch on tape. This term is used when referring to the recording density of the tape unit.
block. A collection of contiguous records recorded as a unit. Blocks are separated by in'terrecord gaps, and each block may contain one or more 'ecords.
control program. A program for allocation and management of system resources.
control statement. A statement that contains information to tailor a program to the requirements of the user.
EBCDIC. Extended binary coded decimal interchange c o d e .
field. A contiguous set of digits or characters that form a m e a n i n g f u l e n t i t y .
fixed length record. A record hilving the same length as other records with which it is logically or physically associated.
format. The general make-up oidata or of a control card.
r e c o r d , o r a f i l e .
initialize. To set counters, switr:hes, and addresses to zero or other starting values at the brlginning of, or at prescribed points in, a comPuter routine.
input. Data to be processed by a computer program.
interblock gap. A blank space on magnetic tape that sep-arates physical records.
loadpoint. The beginning of the usable portion of a reel of tape, indicated by a load point marker, where reading or w r i t i n g is to b e g i n .
Glossary
multifile tape volume. More than one file is stored on a reel of tape.
multivolume tape file. A file stored on more than one tape r e e l .
NRZI (non-return-to-zero IBM). A method of recording on tape where only the one bits are written as magnetized spots on tape.
operand. The representation of a value that must be sup-p l i e d t o d e f i n e a s e l e c t i v e f u n c t i o n t o t h e p r o g r a m . output. The resultant data produced by a computer pro-g r a m .
parameter. A value that must be supplied to define a selec-tive function to the Program'
PE (phase encoding). A method of recording on tape where both zero and one bits are written as magnetized spots. The zero and one bits are opposite in polarity. This method allows distinction between zero bits and no recording.
record. A collection of related data fields.
statement. A meaningful expression or generalized instruc-tion in a source language.
tape labels. Special records at the beginning and ending of t a p e f i l e s . T h e r e a r e v o l u m e , h e a d e r , a n d t r a i l e r l a b e l s . They are used to identify the reel of tape and the recorded d a t a f i l e . T h e y a l s o c o n t a i n c e r t a i n h o u s e k e e p i n g i n f o r m a -t i o n .
tape mark. A special symbol that can be read from or written on magnetic tape. lt is used to indicate the end of a file or file segment, and to segregate the labels from data' Taoe marks must be read in the same density in which they were written.
variable length records. Logical records in a file in which the number of bytes in each record is not a fixed value, but m a y v a r y w i t h i n p r e s c r i b e d l i m i t s '
Glossary 31
lndex
rnagnetic character reader utility 19 special features 25
m o d e l s o t t a p e s u b s y s t e m 2 5 s u b s e t A N S C O B O L 1 8
comparison of characteristics 25 summary of records supported 7
m u l t i f i l e v o l u m e s u m m a r ' o f t a p e s u p p o r t 2 3
l a b e l e d f o r m a t 5 u n l a b e l e d fo r m a t 5 m u l t i p r o g r a m m i n g 1 3 m u l t i v o l u m e f i l e s
l a b e l e d fo r m a t 5 t a p e d a t a m a n a g e m e n t 1 3
u n l a b e l e d fo r m a t 5 t a p e i n i t i a l i z a t i o n 1 4
c o n t r o l s t a t e m e n t s 1 4 t a p e l a b e l s 3
e x t e r n a l 3 header label 1 28
NAME parameter (// F ILE statement) I header label 2 29
i n t e r n a l 3 t r a i l e r l a b e l 1 2 8 t r a i l e r l a b e l 2 2 9 v o l u m e l a b e l 2 7
o u t p u t f i l e s ( t a p e s o r t ) 1 9 t a p e s o r t 1 9
a d d i t i o n a l f e a t u r e s 2 0 c o m p a r i s o n o f l / O r e c o r d s 2 1 f i e l d s e l e c t i o n 2 0
i n p u t f i l e s 1 9
P A R f T Y p a r a m e t e r ll l F I L E s t a t e m e n t ) 1 3 m i n i m u m c o n f i g u r a t i o n 1 9
p r o g r a m p r o d u c t s u p p o r t o u t p u t f i l e s 1 9
b a s i c a s s e m b l e r 2 2 r e c o r d s e l e c t i o n 2 0
d i s k s o r t 2 2 w o r k f i l e s 2 0
F O R T R A N l V 1 9 t a p e s u p p o r t s u m m a r y 2 3
m a g n e t i c c h a r a c t e r re a d e r u t i l i t y 1 9 t r a i l e r l a b e l 1 f o r m a t 2 A
R P G l l 1 8 t r a i l e r l a b e l 2 f o r m a t 2 9
s u b s e t A N S C O B O L 1 8 T R A N S L A T E p a r a m e t e r ll l F I L E s t a t e m e n t ) 1 2
t a p e s o r t 1 9 T Y P E p a r a m e t e r ll l Y O L s t a t e m e n t ) 1 6
R E C F M D a r a m e t e r ll I F I L E s t a t e m e n t l 1 1 u n b l o c k e d r e c o r d s 6 R E C L p a r a m e t e r ( / / F I L E s t a t e m e n t ) 1 | U N I T p a r a m e t e r
r e c o r d a t t r i b u t e s 6 l / F I L E s t a t e m e n t I
r e c o r d s e l e c t i o n ( t a p e s o r t ) 2 0 / / V O L s t a t e m e n t 1 5
r e c o r d i n g d a t a o n t a p e 3 u n l a b e l e d m u l t i f i l e v o l u m e f o r m a t 5 r e c o r d s s u p p o r t e d , s u m m a r y 7 u n l a b e l e d m u l t i v o l u m e f i l e f o r m a t 5
R E E L o a r a m e t e r u n l a b e l e d s i n g l e v o l u m e f i l e f o r m a t 5
l l F I L E s t a t e m e n t 1 0 u t i l i t y p r o g r a m s 1 4
/ / V O L s t a t e m e n t 1 5
R E T A I N D a r a m e t e r ( l l FILE statement) 1 1 R P G I I 1 8
R U N s t a t e m e n t
M o d e l 1 0 c a r d s v s t e m 8 v a r i a b l e le n g t h r e c o r d s 6 , 2 2
t a p e i n i t i a l i z a t i o n 1 4 V O L s t a t e m e n t 1 5
v o l u m e l a b e l f o r m a t 2 7
S E O N U M p a r a m e t e r ( l l F I L E s t a t e m e n t ) 1 3 s e v e n - t r a c k c o n t r o l f e a t u r e 2 6
s e v e n - t r a c k t a p e u n i t f e a t u r e 2 6 s i n g l e d e n s i t y t a p e u n i t f e a t u r e 2 6 s i n g l e v o l u m e fi l e
l a b e l e d fo r m a t 5 u n l a b e l e d fo r m a t 5
work f iles (tape sort) 20
l n d e x 3 3
R E A D E R ' S C O M M E N T F O R M
IBM System/3 Magnetic Tape
Program Planning Manual
GC21-5040-3
YOUR COMMENTS, PLEASE . . .
Y o u r c o m m e n t s a s s i s t u s i n i m p r o v i n g t h e u s e f u l n e s s o f o u r p u b l i c a t i o n s ; th e y a r e a n i m p o r t a n t part of the input used in preparing updates to the publications. All comments and suggestions become the property of lBM.
Please do not use this form for technical questions about the system or for requests for additional p u b l i c a t i o n s ; t h i s o n l y d e l a y s th e r e s p o n s e . I n s t e a d , d i r e c t y o u r i n q u i r i e s o r r e q u e s t s t o y o u r I B M r€presentative or to the IBM branch office serving your locality.
Corrections or clarifications needed:
hge comment
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Technical Newsletter
T h i s N e w s l e t t e r N o . GN21-5604D a t e 3 0 J u n e 1 9 7 8 B a s e P u b l i c a t i o n N o . GC21-5040-3
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