The hierarchical file system does not provide a way to
distinguish
files containing executable scripts from other files.
However, the POSIX standard requires that file permission
bits should be checked to verify that execute access has
been granted to at least one of the file classes as an
indication that a file contains executable statements.
On MPE/iX, when all access would normally be granted to a
user, X access is handled as a special case. Users with
appropriate privilege are granted X access only if the file
has an executable file code (PROG, SL, NMPRG, or NMXL), if
the file access matrix assigns X access to at least one user
class, or if the file has an ACD that assigns X access to at
least one user.
The file owner is granted X access only if the $OWNER ACD entry grants X access. If the $OWNER entry does not exist, the file owner is granted X access if the file has an executable file code or at least one user is granted X access by the file access matrix or an ACD.
A RELEASEd file grants X access to all users.
These rules do not affect other uses of X access on the system, and they are backwards compatible with the use of X access on releases before Release 4.5. Users with appropriate privilege still get X access to files with executable file codes. X is also used to grant STREAM access to JOB files. Users with appropriate privilege can still stream these files because they have R access to
the files.
