Specifications

Using Callable System Routines
10.5 OpenVMS Record Management Services
10.5 OpenVMS Record Management Services
OpenVMS Record Management Services (RMS) assists user programs in
processing and managing files and their contents. RMS is a collection of routines
that give programmers a device-independent method for storing, retrieving, and
modifying data. RMS allows you to create a new file, access an existing file,
extend disk space for a file, close a file, obtain file characteristics as well as to
get, locate, insert, update, and delete records.
Specifically, RMS provides the following:
• Disk file organizations—sequential, relative, and indexed
• Record formats—fixed length and variable length for each file organization
• Record access modes—sequential, by key value, by relative record number, by
record file address
For information about using RMS, refer to the OpenVMS Record Management
Services Reference Manual.
RMS supports unit-record devices such as terminals and printers, but it is
designed primarily to provide a comprehensive software interface to mass-storage
devices such as disk and magnetic tape drives.
10.5.1 RMS File Control Blocks
Control blocks are used to provide input to services and to accept output from
services.
The following control blocks support services that manipulate files:
• File access block (FAB)
The FAB control block includes file specification information, file
characteristics (file organization, record type, allocation information, and so
forth), and run-time access options (file processing information and addresses
of other control blocks with additional information.)
• Optional name block (NAM)
The NAM control block includes supplemental information to the FAB.
• Optional extended attribute block (XAB)
The XAB control block includes file characteristics that supersede or
supplement the FAB control block.
10.5.2 RMS Record Control Blocks
To support services that manipulate with records, there are two record control
blocks, as follows:
• Record access block (RAB)
The RAB control block includes the address of the related FAB control block,
the address of input and output record buffers, general I/O buffer type and
size, how the records will be accessed, and other record information.
• Extended attribute block (XAB)
The XAB control block includes record characteristics that can supersede or
supplement information in the RAB control block.
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