OPS-DIR Review of: 
Importing External PSKs for TLS
draft-ietf-tls-external-psk-importer-05

Note that Brian Carpenter provided a useful review for GEN-ART, far beyond general questions. Brian's comments on Section 6, Incremental Deployment, are relevant to operational considerations, which are the focus of this review.

The draft provides a useful capability and considers possible issues stemming from interaction with (D)TLS 1.2. There are some implementations and other parties are interested.

Nits:

Intro:not expanded on first use
PRF 
KDF

3.1 Terminology: one-too-many "and" in:
...
   *  Imported PSK (IPSK): A PSK derived from an EPSK, External
      Identity, optional context string, and target protocol and KDF.