I installed the Informix softaware in Directory A in AIX, later i want to move this into some other Directiroy B in the same AIX box. In the process of moving this from directory A to B do i need to consider any registry entries like in Windows NT, or directly can i move from A to B other than considering the $INFORMIXDIR variable.
Best you can do is rerun the ids install script after moving to the new directory.
The install script will update the symbolic links in /usr/lib directory that pointed to the old $INFORMIXDIR.
Check also that the variable INFORMIXSQLHOSTS is not set.