ed sometimes clears s bit

[mpiva]

  Ed will only preserve the "S" bit if the name remains EXACTLY the same.

For example, if you have the "s" protection bit on the startup sequence you have to use:

ed S:Startup-Sequence

and not

ed s:startup-sequence

The later will change the upper-case to lower-case and give the file the default "RWED" protection bits.