I have reviewed this document as part of the Operational directorate's ongoing
effort to review all IETF documents being processed by the IESG.

The draft defines the PCE LSP object flag extension. The original 12 bits flags have been allocated, but a new individual draft requires new flags.
In summary, the document is ready, with only small issues.

Major issues:

Minor issues:
Introduction:
The bits from 1 to 3 are assigned in [RFC8623] for Explicit
   Route Object (ERO)-compression, fragmentation and Point-to-Multipoint
   (P2MP) respectively.

[Bo Wu] Here uses ERO object. But the title and abstract say Label Switched Path (LSP) Object Flag Extension, contradict?

5.  Backward Compatibility
   The LSP-EXTENDED-FLAG TLV defined in this document does not introduce any interoperability issues.
[Bo Wu] I feel there are interoperability issues introduced, correct? But the issue will be resolved by the future use?

Nits/editorial comments:
Introduction:
OLD
The bit value 4 is assigned in [RFC8281] for create for PCE-Initiated
   LSPs.  
New
The bit value 4 is assigned in [RFC8281] for creation and deletion for PCE-Initiated LSPs.