sentences:  DR DOS, Inc. failed to comply with the GNU General Public License (GPL) by not crediting the FreeDOS utilities to their authors and including the source code.After complaints from FreeDOS developers (including the suggestion to provide the source code, and hence comply with the GPL), DR DOS, Inc. instead withdrew version 8.1, and also the unaffected 8.0, from its website.APPEND, ASSIGN, BATCH, DBG, DELQ, ERA, ERAQ, MORE and SUBST have been among the internal commands supported since DR DOS 3.31.