The following structure represents a single element of the parser's stack.
Information stored includes:
The state number for the parser at this level of the stack.
The value of the token stored at this level of the stack. (In other words, the "major" token.)
The semantic value stored at this level of the stack. This is the information used by the action routines in the grammar. It is sometimes called the "minor" token.
$major
$minor
$stateno