If you specify an EXPLAIN modifier with a request in 2PC session mode, and that request is followed by a 2PC function, then the SQL portion of the request is explained, but the 2PC function is not.
For example, if you submit the following multiple-statement request, the INSERT and SELECT are explained but the VOTE is not. However, the VOTE is sent to the AMPs.
EXPLAIN INSERT tab1(1,2) ;SELECT * FROM tab1 ;VOTE
VOTE is specified by the system administrator, not by users submitting requests in 2PC mode.