New referral to the EBO: until when can a correction under Rule 140 be requested?

A new referral is pending before the EBO (G 1/10). It concerns a procedural question regarding the timing of a request for correction under Rule 140 (old Rule 89).

The facts of the case are, simplified, as follows: the appellant had based its opposition on added subject-matter. Its sole argument was that claim 1 of the patent as granted contained a feature, "means for initiating a command relating to a position of the device data" that was not disclosed in the original application. The patentee argued that the claim should have read "means for initiating a command relating to a portion of the device data", and position was merely a typographical error. It requested that the opposition be stayed and the patent be sent back to the examining division to correct the "obvious mistake". Both parties agree that if the feature reads indeed "portion", the claim does not contain any added subject-matter, and the opposition is to be dismissed.

The Technical Board of Appeal is basically asking the EBO

1. whether a request for correction under Rule 140 which was filed after initiation of opposition proceedings is admissible and
2. if it is admissible, whether the Opposition Division is bound by the decision of the Examining Division correcting the patent (if any), or whether the Opposition Division can examine whether the correction decision amounts to an unallowable amendment of the granted patent.

Not sure how great the practical importance of this referral is; maybe readers who are prosecutors more than litigators can comment. Seems to this Kat a rather rare case where an (admissible) correction can be decisive for the outcome of an opposition. On the other hand, if there was an obvious error, I don't see why the patentee should be barred from a correction merely because opposition proceedings have been initiated, but maybe I am missing something (I can see the potential for abuse, but is that ever a reason to bar a remedy completely?)