Trouble with some concepts

Hi all,

As announced previously I am currently working with other people on the
translation of PostrgreSQL to French, applications and manuals. We have
stumbled on a couple of concepts which are not very clear to us and
thus do not know very well how to translate. Can someone explain the
following:

msgid "the target relation %u is nailed"

One translator said that "nailed" was used for permanent network
connection. Could this message mean that the relation is locked by a
permanent connection to the database?

msgid "improper qualified name (too many dotted names): %s"

What's a qualified name?

msgid "database name may not be qualified"

Does this mean that the database with some given name cannot be found,
or that the given name is not valid or something else entirely?

msgid ""
"cannot cluster on expressional index when index access method does not
"
"handle nulls"

Is an expressional index an index built on a calculated field (say two
concatenated field or whatever) or something else?

Thanks for the help.

---------------
Francois

Home page: http://www.monpetitcoin.com/

"Would Descartes have programmed in Pascal?" - Umberto Eco