The C source code for tth and ttm has been taken from the testing line
of the Debian Linux distribution which distributes the code under the
GPL version 2. The C source has been created using the flex parser
generator (by running make after unpacking the sources). The flex
sources are not distributed with this R package. A full set of sources
including documentation can be obtained from any Debian mirror, e.g.

 ftp://ftp.debian.org/debian/pool/main/t/tth/
 ftp://ftp.at.debian.org/debian/pool/main/t/tth/
       
Each version which is distributed as part of the R package is also
available at

  http://exams.R-Forge.R-project.org/tth-src/

as original sources, Debian patches and Debian patched version (the
latter is used in the R package).
 
