Control Data 3170 Installation Handbook page 277

TABLE III-9-10 FILE LABEL FIELD DESCRIPTION (Cont'd)
Word Bits
40 23-18
17-00
41
23-00
42 23-00
49 23-00
50
51
52
53
23-00
23-19
18
17-00
23-00
23-00
54 23-00
239 23-18
17-00
III-9-12
Field
rdt
rdn
rblk
r
checksum
r
sdb
dn
lsI
sl
Significance
Class R device type
Zero (not used) for class A or B devices
Device number for class R devices
Zero (not used) for class A and B devices
The number of the block in the RLAB file that
contains a copy of the file label entry (clas s R
devices)
Zero (not used) for class A and B devices
Reserved for future use by I/O system
24-bit binary checksum of entire label. This field
is checked by I/O system to detect accidental modi-
fication of label.
Reserved
Segment down bit; set to 1 if one or more blocks
within this segment could not be written as a result
of hardware access failure; set by CLOSE for all
segments declared down in the FDT.
Number of device on which file segment is stored.
This field is checked against device label to ensure
that proper packs are mounted.
Low segment bit; binary hardware address at which
a file segment begins.
Segment length; number of allocatable units (tracks)
in this segment.
Additional segments to a maximum of 63. Refer
to words 51 through 53.
60410800 A