The PUSHD procedure pushes a directory onto the top of the directory stack maintained by the PUSHD and POPD procedures. The name of the current directory is pushed onto the directory stack. This directory becomes the next directory used by POPD. IDL changes directories to the one specified by the Dir argument. The common block DIR_STACK is used to store the directory stack.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.