Setting "tags" to read only ?

How can we set a tag as read only at creation time ?

We have a tags subdirectory and we keep tags created from trunk there, we
want to set these tags to ready-only so they cannot be modified. We also
copy our tags to a static tag for build reference ( we call this a sliding
tag ). The static tag always has the same name but is always a copy of the
actual tag to be built.

Is it possible to set these tags to read-only once ther are copied from the
trunk to the tags directory ?

thanks

-- 
" The fundamental principle here is that the justification for a physical
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