The text read off it
[02.07.06]
to be taken when the end of a file is reached. A programmer may omit the clause when it is felt no end of file condition will occur with a particular GET. However, when no alternative action is specified through use of the AT END clause, the discovery of an end condition in attempting to GET a record will cause immediate termination of execution of the object program; an error message is printed on-line indicating the cause.
3. Input Error Processing
IOCS automatically attempts to correct most input errors discovered in processing.
a) Input Errors Uncorrectable by IOCS
i. Unrecoverable Redundancy Errors
These are errors typically caused by permanent tape defects and attempts to read tapes in the wrong mode.
ii. Block Checksum Errors
A block checksum error occurs when the checksum of the block written with it on tape does not agree with the checksum calculated at the time the tape is read. Block checksums are not checked unless the Environment SPECIF card option CKSUMS is selected (see section 02.06).
iii. Block Sequence Errors
Block sequence errors occur when an out of sequence block number is discovered. If block sequence checking is desired the Environment SPECIF card option SEQ must be selected (see section 02.06).
iv. Record Length Errors
Record length errors (referred to as EOB errors in the IOCS manual) generally arise when information in a block does not conform with the blocking conventions described by the programmer in the Environment Description. (Records of an input file which span block boundaries cannot be processed unless the SPANS option is specified).
Record length errors are totally unrecoverable by IOCS or the programmer and cause immediate termination of object program execution. An error message is given on the on-line printer.