/// set the pos to the given change
void set(Change const & change, pos_type pos);
/// set the range (excluding end) to the given change
/// set the pos to the given change
void set(Change const & change, pos_type pos);
/// set the range (excluding end) to the given change
void addToToc(DocIterator const & cdit, Buffer const & buffer,
bool output_active, TocBackend & backend) const;
void addToToc(DocIterator const & cdit, Buffer const & buffer,
bool output_active, TocBackend & backend) const;