The following images show order of nodes in correctly defined elements.

Edge (segment): linear and quadratic

Triangle: linear, quadratic and bi-quadratic

Quadrangle: linear, quadratic and bi-quadratic

Polygon: linear and quadratic

Tetrahedron: linear and quadratic

Hexahedron: linear, quadratic and tri-quadratic

Pentahedron: linear and quadratic

Pyramid: linear and quadratic

Hexagonal prism

Polyhedron is defined by

a sequence of nodes defining all facets
a sequence of number of nodes per facet

Nodes:
Node1_of_Facet1, Node2_of_Facet1, ..., NodeN_of_Facet1,
Node1_of_Facet2, Node2_of_Facet2, ..., NodeN_of_Facet2,
Node1_of_FacetM, Node2_of_FacetM, ..., NodeN_of_FacetM
Quantity of nodes per facet:
NbNodes_in_Facet1, NbNodes_in_Facet2, ..., NbNodes_in_FacetM

For example the polyhedron shown in the image below is defined by nodes
[ 1,2,3, 1,4,5,2, 2,5,6,3, 3,6,4,1, 4,7,9,5, 5,9,8,6, 6,8,7,4, 7,8,9 ]
and quantities [ 3, 4, 4, 4, 4, 4, 4, 3 ]

Order of nodes of a facet must assure outward direction of its normal.