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System Modification Program/Extended (SMP/E)
State
The condition of a conversation at a particular point in time. For example, when a
conversation is in receive state, the transaction program cannot send data; it can only
receive data. The state of a conversation determines what procedures a transaction
program can call.
Stream File
A file with a sequential organization. In a stream file, the records can have varying sizes
and each record is stored in a disk or tape region holding approximately the same number
of bytes as in the record. Thus, the record storage regions in a stream file vary from
record to record. In these ways, stream files are similar to sequential files. However,
stream files differ from sequential files in the following ways:
While a sequential file must be accessed on a record basis, a stream file can be accessed on
either a record or byte basis.
Sequential files are stored on disk with the record size at the beginning and end of each
record. Stream files do not have any record size information stored with them; each new
line character in the file is interpreted as the end of a record.
It is possible to have a stream file with only one record. When stream files are used to
store text, each record contains one line of text. Compare with fixed file, relative file, and
sequential file.
Subarea
A division of an SNA network that is under the control of, and addressed by, a front-end
processor or a host access method such as VTAM.
Switched Line
A connection between two or more points that requires the user to dial into a public data
network.
Synchronous
A form of transmission where the sender and receiver exchange clocking or timing
information and send a block or frame with no space or markings between characters.
Because no start/stop bits are required, synchronous transmission is about 25% more
efficient than asynchronous transmission.
Synchronous Communications
Transmission of data at a fixed rate, with the transmitter and receiver synchronized by
means of synchronization characters located at the beginning of each message or block of
data.
Synchronous Data Link Control (SDLC)
SDLC is the synchronous protocol used by SNA. It is level 2 or the link level protocol of
IBM's SNA. SDLC is essentially a subset of HDLC. It provides buffering and polling
capabilities. CA-XCOM runs over SDLC.
System Modification Program/Extended (SMP/E)
An IBM-supplied utility program used to facilitate the installation of software packages
and patches. SMP/E helps ensure that programs are installed in the proper sequence and
that all prerequisites and corequisites are met.
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