ltf.5

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.\" SCCSID: @(#)ltf.5	8.1	9/11/90
.TH ltf 5
.SH Name
ltf - labeled tape facility
.SH Description
.NXB "ltf file" "format"
.NXB "magnetic tape" "labeling"
.NXAM "ltf command" "ltf file"
.NXS "labeled tape facility" "ltf file"
The term "ltf" (Labeled Tape Facility) refers
to the group of programs required to fulfill
the features and functionality outlined here.
.PP
References for the substance of this document are based on:
.IP 1. 4
American National Standard Institute
magnetic tape labels and file structure
for information interchange
ANSI X3.27-1978
.NXR "ANSI X3.27-1978 standard"
.IP 2. 4
The document/working paper: Draft Proposed Revision to ANSI X3.27-1978 
.br
Public Review Comment on ANSI X3L5/83-28T 15-Oct-84
(describes the version 4 ANSI standard)
.PP
This proposed implementation of the 
.PN ltf 
does not claim to  be
100% ANSI standard in all cases. 
That is, the ULTRIX 
.PN ltf 
does not support the entirety of the 
functionality or format capabilities outlined in the 
documents/publications cited as references.
.PP
It should be understood that the functionality and formats for
ULTRIX-labeled tapes are simply based on the standards and
formats referred to, and described in, the publications/documents
listed previously.
.PP
The 
.PN ltf
attempts to follow these documents as working
precepts as accurately as it can, while meeting the needs of
ULTRIX systems.
.PP
It should be further understood that where the cited documents
specify procedures or operational constricts that would conflict 
with those features/functionality normally found in an 
ULTRIX system, the procedures or operational constricts, 
by necessity, have been omitted from the 
.PN ltf 
implementation.
.PP
The goals of 
.PN ltf 
are to create an accurate exchange of information
between ULTRIX systems and between ULTRIX and non-ULTRIX systems as an
import/export facility by providing a means to read/write tapes
in a format generally acceptable to most systems providing support of 
ANSI-labeled tapes.
.PP
It is not a goal of 
.PN ltf 
to provide the multivolume file sets 
or to provide 100% of the ANSI specifications
for the following labels on non-ULTRIX generated volumes:
.EX 0
VOL1
    Accessibility Field
VOL2 - VOL9
UVL1 - UVL9 (User Volume Labels)
HDR1, EOV1, EOF1
    File-set Identifier
    Expiration Date
    Accessibility Field
    Block Count
HDR2
    Buffer Offset Content
HDR3 - HDR9
UHL1 - UHL9 (User Header Labels)
EOV3 - EOV9 (End of Volume Labels)
EOF3 - EOF9 (End of File Labels)
ULT1 - UTL9 (User Trailer Labels)
.EE
The FORMATS
section provides the general ANSI volume and label formats.
Each label consists of 80 bytes of ASCII data as specified. 
Items enclosed in parentheses () indicate optional fields that 
may be present according to the ANSI standard. 
The following terms are used as indicated:
.TP 5
"a" 
Refers to the sets of characters including
uppercase (A-Z), 
numerals (0-9), and special characters (space ! " % & ' ( ) * + , - _ . / : ; < = > ?).
.RE
.TP 5
BLOCK
.NXR "block" "defined"
A group of consecutive bytes of data treated as a unit by the storage 
medium.  
Blocks are separated by an interblock gap. 
A block may contain part of a record, all of the record, or many 
records.
.TP 5
BLOCK LENGTH
.NXR "block length" "defined"
The minimum block size is 18 bytes and the maximum is 20480.
.TP 5
RECORD
.NXR "record" "defined"
A set of related data treated as a unit of information:
.TP 5
TAPE MARK
.NXR "tape mark" "defined"
A control block used as a delimiter.
.PP
FORMATS for ANSI VERSION 3/4  -  MULTI-FILE / SINGLE VOLUME
.NXB "ltf file" "label formats"
.EX 0

bot      Beginning of tape marker
VOL1     Volume Label (only 1 permitted for ANSI version 3,
         ANSI version 4 OPTIONALLY permits Volume Labels
         2 through 9)
(UVLn)   OPTIONAL User Volume labels ('n' varies from 1 - 9)
HDR1     First File Header Label
HDR2     Second File Header Label
(HDRn)   OPTIONAL File Header Labels ('n' varies from 3 - 9)
(UHLa)   OPTIONAL User File Header Labels (quantity
         unspecified)
tm       Tape Mark
DATA     data blocks of first file
tm       Tape Mark
EOF1     First End of File Label
EOF2     Second End of File Label
(EOFn)   OPTIONAL End of File Labels ('n' varies from 3 - 9)
(UTLn)   OPTIONAL User Trailer Labels
tm       Tape Mark

HDR1     First File Header Label
HDR2     Second File Header Label
(HDRn)   OPTIONAL File Header Labels ('n' varies from 3 - 9)
(UHLa)   OPTIONAL User File Header Labels (number undefined)
tm       Tape Mark
DATA     data blocks of second file
tm       Tape Mark
EOF1     First End of File Label
EOF2     Second End of File Label
(EOFn)   OPTIONAL End of File Labels ('n' varies from 3 - 9)
(UTLn)   OPTIONAL User Trailer Labels
tm       Tape Mark

HDR1     First File Header Label
 .
 .
 .	
tm       Tape Mark
tm       Tape Mark
.EE
.sp
VOL1 - Label Format - ANSI VERSION 3

The following table identifies the volume and supplies 
volume security information:
.EX 0 
Size   First &  Description
of     Last 
Field  Byte #   or Content
-----  -------  -----------

3      1 - 3    "VOL"
1      4        "1"
6      5 - 10   Volume Identifier - user specifiable "a"
                characters, default = "ULTRIX"
1      11       Accessibility Field - not implemented by ltf
26     12 - 37  Reserved by ANSI (spaces)
14     38 - 51  Owner ID - user defined "a" characters,
                default = spaces
28     52 - 79  Reserved by ANSI (spaces)
1      80       Label Standard Version, 3 for ANSI Version 3
.EE
.sp
VOL1 - Label Format - ANSI VERSION 4

The following table identifies the volume and supplies volume 
security information:
.EX 0
Size   First &  Description
of     Last 
Field  Byte #   or Content
-----  -------  -----------

3      1 - 3    "VOL"
1      4        "1"
6      5 - 10   Volume Identifier - user specifiable "a"
                characters, default = "ULTRIX"
1      11       Accessibility Field - not implemented by ltf
13     12 - 24  Reserved by ANSI (spaces)
13     25 - 37  Implementation ID - "a" characters, ULTRIX
                default = "DECULTRIXnnnn", where nnnn are
                digits from 0000 to 9999, identifying the
                version number of ltf which created volume
14     38 - 51  Owner ID - user defined "a" characters,
                default = spaces
28     52 - 79  Reserved by ANSI (spaces)
1      80       Label Standard Version, 4 for ANSI Version 4
.EE
.sp
HDR1 - Label Format - ANSI VERSION 3/4

The following file header label identifies and describes the file.
Information in this label is limited to "a" characters only:
.EX 0
Size   First &  Description
of     Last 
Field  Byte #   or Content
-----  -------  -----------

3      1 - 3    "HDR"
1      4        "1"
17     5 - 21   File ID - Interchange file name, "a"
                characters
6      22 - 27  File Set ID - "000001" since only one
                file set on single volume
4      28 - 31  File Section Number - "0001"
4      32 - 35  File Sequence Number - starts at "0001"
                and increments once for each file on volume
4      36 - 39  Generation Number - "0001"
2      40 - 41  Generation Version Number - "00"
6      42 - 47  Creation Date - Julian date, first character
                denotes century, " " = 1900, "0" = 2000
6      48 - 53  Expiration Date - Julian date, not implemented
                by ltf, set to " 99366"
1      54       File Security - " "
6      55 - 60  Block Count - "000000" 
13     61 - 73  Implementation ID - same as in VOL1
7      74 - 80  Reserved by ANSI (spaces)
.EE
.sp
HDR2 - Label Format - ANSI VERSION 3/4

File header label describes the record format,
maximum record size, and maximum block length of the file.
Information in this label is limited to "a" characters, except
for the content of bytes 16 through 50 if volume is ANSI version 4.  The
contents of the field in bytes 16 - 50 are for ULTRIX implementation
only; thus, if volume is not ULTRIX, these fields are ignored.
.EX 0
Size   First &  Description
of     Last 
Field  Byte #   or Content
-----  -------  -----------

3      1 - 3    "HDR"
1      4        "2"
1      5        Record Format - "F" = fixed length records
                                "D" = variable length records
                                "S" = segmented records
5      6 - 10   Block Length - default = "02048"
5      11 - 15  Record Length - "F" format, length of each data
                                record
                                "D" format, maximum length of a
                                data record including record
                                control word
                                "S" format, maximum length of a
                                data record not including the
                                segment control word, if scw =