Oh, I overlooked this Comment, and it clears up everything. When you said "the line disappears on posting the Comment", I assumed you could not see it in the Comments list. I never realized that you were commenting on the Interactive Diagram page, and looking at it there. So we were in fact doing different things. (And by that time we had already exchanged so many messages on this page that the offending Diagram was no longer there anyway.)
On the Interactive Diagram page there is a Diagram with an explicit pieceTable. You might not see it, because it is in the Design Wizard. Which is initially hidden, and will become visible in parts during the design process of a new Diagram. There it is used as the table you must use to set up the initial position. But even when not visible it is still on the page, so I suppose it is that table which actually gets filled with the piece overview of the Diagram that you posted. So it is not just that the Diagram posted in the comment was missing the subscript line; it was also wrecking the Design Wizard. But I guess no one uses that anymore now that we have the Play-Test Applet.
Anyway, the damage to the posted Diagram should eventually cure itself, because it is pushed off the article page by new Comments. But to prevent Diagrams posted in Comments on the Interactive Diagrams page from interfering with the Diagrams in the article, I now used a satellite=design parameter in the Diagram that is used in the Design Wizard, and gave the table from which users have to drag the pieces id="designTable" instead of pieceTable. This should make the piece table in the Wizard invisible to other Diagrams on the page. When I created the Design Wizard the satellite parameter did not exist yet.
Oh, I overlooked this Comment, and it clears up everything. When you said "the line disappears on posting the Comment", I assumed you could not see it in the Comments list. I never realized that you were commenting on the Interactive Diagram page, and looking at it there. So we were in fact doing different things. (And by that time we had already exchanged so many messages on this page that the offending Diagram was no longer there anyway.)
On the Interactive Diagram page there is a Diagram with an explicit pieceTable. You might not see it, because it is in the Design Wizard. Which is initially hidden, and will become visible in parts during the design process of a new Diagram. There it is used as the table you must use to set up the initial position. But even when not visible it is still on the page, so I suppose it is that table which actually gets filled with the piece overview of the Diagram that you posted. So it is not just that the Diagram posted in the comment was missing the subscript line; it was also wrecking the Design Wizard. But I guess no one uses that anymore now that we have the Play-Test Applet.
Anyway, the damage to the posted Diagram should eventually cure itself, because it is pushed off the article page by new Comments. But to prevent Diagrams posted in Comments on the Interactive Diagrams page from interfering with the Diagrams in the article, I now used a satellite=design parameter in the Diagram that is used in the Design Wizard, and gave the table from which users have to drag the pieces id="designTable" instead of pieceTable. This should make the piece table in the Wizard invisible to other Diagrams on the page. When I created the Design Wizard the satellite parameter did not exist yet.