Dear Hongfu, The key word “MODIFIED” sets up a hierarchical expansion which has a boundary-interior decomposition. In 1D this is a series of modified Legendre polynomials supported by the linear finite element shape functions. Then a Quadrilateral element will be made up by a tensor product of this basis in a classical approach to p-type modal elements. Hope this helps. Cheers, Spencer. On 21 Apr 2016, at 03:24, Hongfu Zhang <hongfu2233@gmail.com<mailto:hongfu2233@gmail.com>> wrote: Hi all, Look at the words in XML "<E COMPOSITE="C[0]" NUMMODES="5" FIELDS="u" TYPE="MODIFIED" />" I would like to know what the default basis type for the "MODIFIED" ? Regards! Hongfu Zhang _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users Spencer Sherwin McLaren Racing/Royal Academy of Engineering Research Chair, Professor of Computational Fluid Mechanics, Department of Aeronautics, Imperial College London South Kensington Campus London SW7 2AZ s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052