I wish to ask does Sofistik software have technical manual for result interpretation, such as diagram showing positive value is referred to as compression force or tension force, what is the meaning of principal membrane forces n-I, principal membrane forces n-II, how is the axis is referred to and so on.
For local coordinate systems and internal forces (beams/quads) look at sofimsha manual page 2-4.
Tension is positive (according to convention).
In general the definition of directions/magnitudes etc can be found in the manual of the program defining the input or performing the calculation. (e.g. aqua/sofimsha/ase show element definitions)