BUILT-IN WOLFRAM LANGUAGE SYMBOL
is an option for Trace and related functions that specifies whether symbols such as x should match symbols with local names of the form x$nnn.
- The default setting is MatchLocalNames->True.
- With the default setting, Trace[expr,x=rhs] will show assignments to local variables whose names are of the form x$nnn.
- Trace[expr,x=rhs,MatchLocalNames->False] shows assignments only for the global symbol x.