The Core Scheme unit recognizes that identifiers may be free or (lexically) bound. To accomodate additional binding forms, a distinction is first drawn between free and bound variables:
top-level-varref : varref ()
bound-varref : varref (binding)
One sub-type of the latter is also defined:
lexical-varref : bound-varref ()
The binding {htmlonly field (in the sense of eq?).
NOTE: There is no justification for binding to be a sub-type of parsed; this dependency will be elided.