/// return the type of vertical space
vspace_kind kind() const;
/// return the length of this space
/// return the type of vertical space
vspace_kind kind() const;
/// return the length of this space
/// the latex representation
string const asLatexCommand(BufferParams const & params) const;
/// the size of the space on-screen
/// the latex representation
string const asLatexCommand(BufferParams const & params) const;
/// the size of the space on-screen