SPECTRA or SPA is the data reduction program at the Five College Radio Astronomy Observatory for use with single dish spectral line or continuum data. It was originally written by Nick Scoville in 1978 for the reduction of millimeter wave data generated by the 14 meter telescope of the Five College Radio Astronomy Observatory using FORTRAN 66 programming language. Due to the severe limitations of memory and hard disks available on computors in that era, the program was written with very small memory and disk requirements. In 1989, the program was rewritten in FORTRAN 77. In addition, machine dependent code was isolated into blocks so that a preprocessor can translate the code to any of five target architectures and operating systems. These include SunOS UNIX, VAX/VMS and PC-MSDOS. In 1990-91, the command parser, directory structures, and tape format were radically altered to remove the major limitations to the program which included the 1000 scan capacity of the data file, the 300 scan limit to the input arguments, and the fixed record length of a scan. In addition, the control loop of the program was modified to accomodate a secondary scan structure specific to data from an array receiver. All of these changes are compatible with older data and tape formats. Data files created with previous versions of the program can be updated to the present revision of the program.