Question

We need to set up a way to limit access (in OPAC) to certain collections.  We have a subset of employees who are not authorized to see these particular documents.  Actually, if we could block the url in the catalog record (title is not a problem) that would be ideal. How can we do this?

Answer

If you don't want a field (such as the URL field) to appear in OPAC for anyone, it can be omitted from your xxx01 edit_doc_999.eng, but the assumption here is that you *do* want it to be viewable in the OPAC by certain users, but not others. 

The Aleph z61 (Patron Profile) record has eight "Denied library" fields (z61_denied_library_1, etc.). Each of these is a Logical base to which the user is denied access. 

You could specify (via tab_base.eng) that these records are part of a particular base. (This presumes that the records have some field or search term in common which can be used to distinguish them and could be added to column 9 of the tab_base.eng entry.) 

Assuming so, you could have the z303 (Global patron) record of patrons who are not allowed to access these docs point to a z61 profile with Denied-libarary = <this base>. 

Of course, the effect of this would be to prevent these users from seeing these records at all. If you want them to be able to see the record but not see the URL field or such ... it's unclear just how that could be done. 

Additional Information

Note:  Though it wouldn't work in this particular case, if you want to allow only users who are signed in to see records belonging to a particular base, that can be accomplished via tab_base.lng column 2 ("Access limited to signed-in users").