This type of ternary graph allows you to examine the relations between four or more dimensions (X, Y, Z, and V1, V2, etc.) as a 3D trace plot where three of those dimensions (X, Y, and Z) represent components of a mixture (i.e., the relations between them is constrained such that the values of the three variables add up to the same constant for each case). Data points in this graph are positioned as in regular 3D scatterplots, however, individual data points are connected with a line (in the order in which they were read from the data file), visualizing a "trace" of sequential values.

See also, 3D Ternary Plots and Graphs - Ternary Graphs.