problem finding mktemp in info file

[Stepan Kasal]

Hello,
  "man mktemp" points me to
        info coreutils 'mktemp invocation'
but no such node exists.

The particular question was what does the following mean:
  -t               interpret TEMPLATE as a single file name component,
                     relative to a directory: $TMPDIR, if set; else the
                     directory specified via -p; else /tmp [deprecated]

is only the default with /tmp deprecated, or is any usage of -t
deprecated?  What shall I do instead of "mktemp -t foo.XXXXXX"?
mktemp "$TMPDIR/foo.XXXXXX"  ?   Why?
I hoped to find the answers for these questions in the info file.

Have a nice day,
        Stepan Kasal