The code used to compute Social Security benefits in the Social Security Benefit Calculator and other programs is comprised of two libraries, named Misc Library and PiaData Library. The code in the Misc Library provides some basic functions independent of benefit calculations. The code in the PiaData Library is used to calculate benefits. 

All of the code for both libraries is in subdirectories of the oactobjs32 directory. Generally, the header files for both libraries are in the include subdirectory, while the source files are in the misc and piadata subdirectories. A few header and source files are in the windows subdirectory, where the code is specific to the Windows platform. 

All of the code for output from the Social Security Benefit Calculator is in the PiaOut Library, stored in the piaout subdirectory of the oactobjs32 directory. 

The primary calculation class is PiaCal (in the PiaData Library), which is the parent of classes that actually control the calculation of a Social Security benefit.