doc: Distinguish the "nar bundle" format from "nar".

* doc/guix.texi (Invoking guix archive): Introduce the term "nar bundle"
and clarify what the output of "guix archive --export" really is.
* guix/nar.scm (restore-one-item, restore-file-set): Use the term "nar
bundle" in docstrings.

1 files changed, 11 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index bad2d36e42..db2013c16b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4990,7 +4990,13 @@ what you should use in this case (@pxref{Invoking guix copy}).
 
 @cindex nar, archive format
 @cindex normalized archive (nar)
-Archives are stored in the ``normalized archive'' or ``nar'' format, which is
+@cindex nar bundle, archive format
+Each store item is written in the @dfn{normalized archive} or @dfn{nar}
+format (described below), and the output of @command{guix archive
+--export} (and input of @command{guix archive --import}) is a @dfn{nar
+bundle}.
+
+The nar format is
 comparable in spirit to `tar', but with differences
 that make it more appropriate for our purposes.  First, rather than
 recording all Unix metadata for each file, the nar format only mentions
@@ -5000,6 +5006,10 @@ entries are stored always follows the order of file names according to
 the C locale collation order.  This makes archive production fully
 deterministic.
 
+That nar bundle format is essentially the concatenation of zero or more
+nars along with metadata for each store item it contains: its file name,
+references, corresponding derivation, and a digital signature.
+
 When exporting, the daemon digitally signs the contents of the archive,
 and that digital signature is appended.  When importing, the daemon
 verifies the signature and rejects the import in case of an invalid