AS-17 Segment reporting

AS-17 apply to consolidated financial statement if entity prepare consolidated FS.

and not to stand alone FS.

hence if entity prepare stand alone FS only then it will apply to Stand alone FS.

any segment become reportable segment if it qualifies any of the following method..

method 1.     limit methd:- if any segment qualify any of following limit then such segment become reportable seg.

         Limit A      segment revenue is 10% or more of total segment revenue

         Limit B        segment result is 10% or more of total segment result.

         Limit C       segment asset are 10% or more of segment asset.

Method 2. any segment become reportable by the choice of management.

Method 3   if any segment become reportable in previous year because it had qualified any limit, then it would be reportable in current year also.

So according to your question A is reportable segment but B can become reportable in current year either by choice of management or it had qualified any of limit in previous year.

in such a situation only management thinks tht b segment should be reportable ..

than it covers under operating segment which is reporatble....

As per AS17on  Reportable Segment, this AS is applicable on Consolidated financial statement

If Company prepare CFS, then management may by choice report segment B