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Compaq FTAM Responder Support of
ISO FTAM Functions
OSI/FTAM Responder Manual—425199-001
4-5
Mapping Between FTAM Contents Types and
Compaq File Structures
FTAM-2 files are relative (sequential) files, and each logical record of a relative file can be a maximum of 4072
bytes. Each string is stored as a logical record in a relative file. Therefore, the practical size limit of a string during
data transfer is 4072.
∗∗
If the string-significance parameter is set to fixed or variable, the file is an entry-sequenced file and is subject to the
maximum logical record length of 4072 bytes. However, if a DEFINE by the name
_ZOSF_FIXED_AS_UNSTRUCT exists when the FTAM processes are started then with the string-significance set
to FIXED, the file will be an unstructured file with a maximum-string-length of 4096 bytes.
∗∗∗
This value represents the Compaq FTAM responder default for NBS-9 files. If you open an NBS-9 file without
specifying the file attributes to return, the Compaq responder defaults the parameter setting to the filename attribute
only. If you do specify file attributes, the Compaq responder returns the specified file attributes.
Mapping Between FTAM Contents Types and
Compaq File Structures
The FTAM virtual filestore (VFS) supports the Compaq responder by providing an
interface to the Guardian file system. The Compaq implementation of the VFS maps
Compaq FTAM file structures and attributes to Guardian file structures and attributes,
and vice versa. Tables 4-6 and 4-7 show mappings of FTAM document types to file
types.
Create Mappings
Table 4-6 shows the Guardian file structures created when you use the F-CREATE
service to create FTAM files, provided either the file does not exist or the override
parameter is set to delete and create with new attributes. (If the file exists and the
override parameter is set either to select the old file or to create a new file with the old
attributes, the existing file attributes are not checked and are left unchanged.) The table
also shows the default parameter values for the FTAM-1, FTAM-2, and FTAM-3
document types. This table indicates the default parameter values for the document
types that Compaq supports, whereas Table 4-5, earlier in this section, indicates the full
range of parameter values for these document types.
For the create service to succeed, the maximum-string-length parameter is optional,
because the ISO FTAM default value for this parameter, unbounded, is supported by the
Compaq responder. Further, the value of the maximum-string-length parameter must
maximum-string-length 1-4072 (in bytes)
string-significance fixed or variable**
NBS-9 Not applicable <filename>***
Table 4-5. Document Types and Parameters Supported by the Compaq FTAM
Responder (continued)
FTAM
Document
Types Parameters Parameter Values