ISO Pascal reference manual

Errors and debugging
correct use of features which the error indicates have been misused. In the
error message statements, any item enclosed in angle brackets e.g.
< something > will be replaced by an item appropriate to the context of the
message.
5.1.3 Fatal compile errors
Certain errors cause the compiler to abort the compilation without trying to
analyse the rest of the Pascal program.
Fatal errors are marked by the text
*FATAL ERROR nnn --
followed by the reason for stopping. The only way to prevent the same fatal
error occuring again is to change the program in the way recommended.
For example, if the fatal error was caused by the end of program token
`end.' being encountered too soon, look through the source for a `.' where
there should be a ;'.
The range of FATAL errors produced by the compiler is listed in Appendix
B.
5.2 Run-time errors
When an error is detected at run-time, an event is signalled to the diagnostic
package which generates a post-mortem backtrace of the error.
Following the report of the nature of the error, information is displayed
about the environment of the statement causing the error. This information
includes the line number at which the error was detected, the name of the
block containing that line, and the values of any local variables declared in
that block.
If no value has yet been given to a variable, its value is printed as 'not
assigned'. Large integer values will be printed in both decimal and
hexadecimal (base 16) representations. If an integer value corresponds to
the ASCII code for a printable character, then that character will be
displayed as well. This process is repeated for the statement (usually a
procedure call) which invoked this block, and so on back to the start of the
program. Finally, the error and information about where it occurred is
repeated in case the original copy has been scrolled off the top of the screen.
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