POV-Ray source code is distributed in archives with files arranged in a particular hierarchy of directories or folders. When extracting the archives you should do so in a way that keeps the directory structure intact. In general we suggest you create a directory called povray3 or povray31 and extract the files from there. The extraction will create a directory called source with many files and sub-directories.
In general, there are separate archives for each hardware platform and operating system but each of these archives may support more than one compiler. For example here is the directory structure for the MS-Dos archive. Other platforms use similar structures.
SOURCE
SOURCE\LPNG101
SOURCE\ZLIB
SOURCE\MSDOS
SOURCE\MSDOS\PMODE
SOURCE\MSDOS\BORLAND
SOURCE\MSDOS\DJGPP
SOURCE\MSDOS\WATCOM
The source directory contains source files for the generic parts of POV-Ray that are the same on all platforms. The source\lpng101 contains files for compiling a library of routines used in reading and writing PNG (Portable Network Graphics) image files. The source\zlib contains files for compiling a library of routines used by libpng to compress and uncompress data streams. All of these files are used by all platforms and compilers. They are in every version of the source archives.
The source\msdos directory contains all source files for the MS-Dos version common to all supported MS-Dos compilers. The pmode sub-directory contains source files for pmode.lib which is required by all MS-Dos versions. The borland, djgpp, and watcom sub-directories contain source, makefiles and project files for C compilers by Borland, DJGPP and Watcom.
The source\msdos directory is only in the MS-Dos archive. Similarly the Windows archive contains a source\windows directory. The Unix archive contains source/unix etc.
The source\msdos directory contains a file cmpl_msd.doc which contains compiling information specific to the MS-Dos version. Other platform specific directories contain similar cmpl_xxx.doc files and the compiler specific sub-directories also contain compiler specific cmpl_xxx.doc files. Be sure to read all pertinent cmpl_xxx.doc files for your platform and compiler.