GENER detects errors caused by invalid post-processor commands, inappropriate control of the NC machine and incompatibilities due to invalid QUEST responses. In all cases, processing of the CL file continues until the FINI record is read.

Error messages are textual. They identify a problem (or event), the severity of the problem, and any corrective action taken. Also listed are statistical and positional information for the error. For example:

Warning: CUTCOM Option LENGTH is not supported by this machine and cannot be simulated. Option ignoredSEVERITY(04) ISN(0035) CLREC(0041) ERRNUM(01524001)

Error messages contain three items: the type, text and status line. If the error occurs from within a macro, there may also be a message that indicates the position of the error within the macro. An additional line may also be output that indicates that the macro was terminated due to a serious error.

There are four types of error messages: Message, Warning, Error and Fatal. The message and warning type errors are generated when an unexpected event occurs for which the post-processor can correct. Error and fatal type messages are generated when the post-processor detects an error that it cannot correct or make an assumption about.

The text portion of the error message begins with the post-processor word that generated the error message. The text body contains the error description, that includes any corrective action taken. For example, suppose the user coded the command LOADTL/1,OSETNO,3. During post-processing, the following message was output:

Warning: CUTCOM [Called by LOADTL] Option LENGTH is not supported by this machine and cannot be simulated. Option ignored.SEVERITY(04) ISN(0035) CLREC(0041) ERRNUM(01524001)

The OSETNO option on the LOADTL command invoked a call to the CUTCOM command that handles cutter length compensation. However, the CUTCOM logic detected that cutter length compensation was not supported and it output the appropriate error message. This particular example is one of an error message generated on an indirect call. GENER tracks all indirect calls and places them at the beginning of the error message text.

The error status line is output after the text portion of the error message. Four items display on this line. They are the error severity (SEVERITY), internal sequence number (ISN), the CL record number (CLREC) and the GENER error number (ERRNUM). The error severity indicates the severity level of the message and may have any value between 0 and 99. A value between 0 and 3 signifies a "message." A value between 4 and 7 signifies a warning message. A value between 8 and 15 signifies an error message. Finally, a value between 16 and 99 signifies fatal message. The ISN points to the original APT source statement that caused the error. The CLREC is the Section III record number generated by the APT CL-Editor on which the error was found. The error number refers to the GENER system error number.

If the error occurs while processing a macro line, the macro is identified and the macro line causing the error is output. If an error occurs while evaluating a macro expression or executing a special macro command and the severity is greater or equal to 8, a TERMAC statement is generated to exit the macro and the following message is output:

*** TERMAC generated due to error(s).