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message when interactive debug is entered, an indication of a syntax error when in interactive
debug, or the traceback clauses after a syntax error in the program (see below).
>>> Identifies the result of an expression (for TRACE R) or the value assigned to a variable during
parsing, or the value returned from a subroutine call.
>.> Identifies the value “assigned” to a placeholder during parsing (see page 204).
The following prefixes are used only if TRACE Intermediates is in effect:
>C> The data traced is the name of a compound variable, traced after substitution and before use,
provided that the name had the value of a variable substituted into it.
>F> The data traced is the result of a function call.
>L> The data traced is a literal (string, uninitialized variable, or constant symbol).
>O> The data traced is the result of an operation on two terms.
>P> The data traced is the result of a prefix operation.
>V> The data traced is the contents of a variable.
If no option is specified on a TRACE instruction, or if the result of evaluating the expression is null, the
default tracing actions are restored. The defaults are TRACE N , command inhibition (!) off, and interactive
debug (?)off.
Following a syntax error that SIGNAL ON SYNTAX does not trap, the clause in error is always traced. Any
CALL or INTERPRET or function invocations active at the time of the error are also traced. If an attempt to
transfer control to a label that could not be found caused the error, that label is also traced. The special
trace prefix +++ identifies these traceback lines.
TRACE
Chapter 13. Keyword Instructions 169