[Help-tar] Internal documentation for ".snar" files?

[Dr Rainer Woitok]

Greetings,

I'm looking for a documentation explaining  the layout of ".snar" files.
>From listing a ".snar"  file using the  "strings" command I already know
that numerical strings are either access rights  or time stamps and that
for directories the relative paths are listed, followed by anything con-
tained  therein.  Here it seems  sub-directory names  are prefixed  with
"D", ordinary files which are existing but are not  included in the last
incremental are prefixed with "N" and new or modified ordinary files are
prefixed with "Y".

But looking at the "tar" source files, I can see that apart from "D" and
"N" also the  characters "I", "R", "T",  and "X" are used.  Judging from
the source code I  assumed "R"  and "T" are  used to specify  "from" and
"to" paths  associated with  a renaming  operation, but  moving both, an
ordinary file and  a sub-direcory  in a test  directory  caused  the old
names to disappear from the ".snar" file completely and the new names to
be prefixed with "D" and "Y", respectively.

Could anyone shed some more light onto this?

Sincerely
 Rainer