|Lesson 1A||Lesson 1B||Lesson 2X||Lesson 2A||Lesson 2B||Lesson 2C||Lesson 2D|
Read Document 2X.
Where it applies, you could answer such questions as:
Note that parse calls upon the file parse.inp for input directives. The directive *TRACE=T causes every step in the building (and rebuilding) of the parse tree to be printed, i.e. records every call on the BNF definitions of the grammar. To turn off the BNF trace, replace *TRACE=T by *TRACE=F.
In the file parse.inp the directive *TRACER=T causes every step in the execution of all restrictions to be printed. If only a particular restriction is of interest, e.g. WAGREE, the form is
A companion directive *TRACERTREE(WAGREE)=T provides a short
version of the parse tree at the time WAGREE is executed. In
the parse.inp file for this lesson, no *TRACER=T is supplied;
instead we have
Other restrictions can be traced in the same manner.