Most file systems permit the modification of file attributes after a file is created. However, some file systems do not. In some file systems, some attributes of directories cannot be changed. In some file systems, some attributes of files cannot be changed. Some file systems have times associated with file access which may not be changed without the access being made. FTAM file stores are examples of file systems which may not permit some attributes to be changed. Consequently, the IEEE 1003.1-1990 functions chmod(), chown(), and utime() may not be able to manipulate the supported file attributes (see sec. 4.2.1 and sec. 4.2.2) by a file system.