The syntactic and semantic aspects of the formal language of general system
logical theory (GSLT) are presented. Following an introduction to the lang
uage of GSLT, we show the power of GSLT in a number of different areas. One
possible model for GSLT is category theory. The categorical structures we
formally expressed by a network of elementary logical system (ELS), basic c
omponents of GSLT. GSLT uses the input-output paradigm to transform the sta
tic classical form of categorical structures to dynamic transformations of
objects and morphisms. Connection with general system theory and Klir's gen
eral system problem solver (GSPS) is given.