Control Data 3170 Installation Handbook page 275

Word
22
23
24
25
26
27
1II-9-10
Bits
23-18
17-12
11-00
23-00
23-00 }
23-00
23-18
17-15
14
13-12
11-00
23-12
11-00
TABLE III-9-10 FILE LABEL FIELD DESCRIPTION (Cont'd)
Field
cIs
v
r
filesize
nasak
rm
rf
bf
r
Irs
max
tis
Significance
Class
o
Clas s B device
1 Class A device
2 Class R device
Version; applicable to MASTER; zero for MSOS.
Reserved
Contains, as a binary integer, the number of allo-
catable units (tracks) assigned to file (0 < file size
< 223).
Next available SAK; block number (record 1) where
next record can be written within file.
Record mark; character which terminates each
record when record format is record mark variable.
Record format; denotes type of records within file
o
Fixed length records
1 Key field contains total number of
characters
2 Key field contains number of occurrences
of a fixed length trailer item
3 Universal format
4 Record mark specified by rm terminates
each record
Block format
1 One logical record per block
o
Logical records are blocked; each block
contains a 2-word header which specifies
the next block number (NBN) and the posi-
tion of the first available character within
the block (POFAC).
Reserved
Logical record size (number of characters) of fixed
length record; size of fixed portion of variable
records which have trailer items; 0 if records vary
by key field or record mark.
Maximum logical record size; maximum size, in
characters, of variable portion of logical records.
For variable records with trailers, size of trailer
item times maximum number of occurrences. For
all others, maximum size of record within file.
Trailer item size in characters if rf=2; otherwise, O.
60410800
A