FATCAT (Fortran Advanced Technology Code Analysis Tool) is a software tool designed to aid the programmer in maintaining, modifying, and enhancing substantial production programs (a thousand to over a million lines long). FATCAT is also extremely useful in aiding the programmer in parallelizing Fortran code. FATCAT analyzes sequential code written in ANSI Fortran '77. It also 'understands' Cray Fortran (CFT) extensions, such as recursion and pointer variables. Like some cross-reference-table producing tools, FATCAT also understands the effects on variable usage of COMMON and EQUIVALENCE statements. Unlike most such tools, however, it also accounts for the effects of SUBROUTINE and FUNCTION calls, including recursive calls, of array subscripting, and of dereferencing CFT-style pointer variables.>