ONIX for ISTC Metadata

EDItEUR and the International ISTC Agency(IIA) have developed an ONIX format to be used by ISTC registrants and Registration Agencies for two-way communication related to the processes of registering a new ISTC work or amending the metadata associated with an existing ISTC work record. A draft version of the format (the IIA recently approved the publication of Version 1.0) can now be found on the EDItEUR website as ONIX ISTC Registration Format <http://www.editeur.org/106/ONIX-ISTC-Registration-Format/>

This is an important milestone for practical work identifiers.

I have two questions.

1. I have not been following ISTC closely for some time, and as I look at its web pages I wonder What relation the ISTC concept of work has to FRBR?

I recall there was considerable difference from FRBR in how the ISTC effort conceptualized a work. Is that still true. The ISTC about web page says the ISTC reference works not manifestations, but I didn’t find any definition of work nor any reference to a concept like expression.

2. How might ISTCs be used in WorldCat to collocate records for the same works?