Triple DES Standard?

[Rodney Thayer]

Is there a "standard" for Triple DES, in 2-key or 3-key mode?
I don't see it in the FIPS documents, and all the IPsec RFC's
reference the 1979 Tucman article, other than that everyone seems
to point at Schneier or some other book.
 
Is there an official (in any sense) "standard" for it?