When does chapter selector show?

I have two different appendices (a timeline and a glossary) in a Bible app, and when you select the book of the first one, it asks you to select the chapter (even though there is only one chapter). Here is what the SFM looks like for it:

\id BAK
\mt1 Taariikh al‑Ahad al‑Gadiim 
\pc (Al‑siniin dool ma muhaddadiin sawa sawa laakin gariib le l‑wakit da.) 
\b 
\tr 
\th1 Taariikh gubbaal waaluudit Isa al‑Masiih
...

But when you select the second one, it takes you directly to the book without showing the chapter selector. Here is what that SFM looks like for it:

\id GLO ‑ Chadian Arabic RS
\mt1 Tafsiir al‑kalimaat al‑gaasiyiin
\li1 \k Afraayim\k* Hi akbar gabiila al‑gaaʼide fi mamlakat Israaʼiil fi l‑munchaakh. Wa fi kutub al‑anbiya, al‑usum Afraayim yimassil mamlakat Israaʼiil kullaha. (Éphraïm)
\li1 \k araba/arabaat\k* Al‑araba fi l‑zaman daak, hi kaarro al‑yukurruuh be kheel le yihaarubu beyah. (chariot)

Is there something magic about the book id, or something in the SFM markers which tells it not to ask for the chapter number? It would be nice to avoid that chapter selection step in the first appendix, since there is only one chapter to select. (Note that the first appendix has two \mt1’s. But I changed the second one to an \mt2 and the chapter selector still appeared, so that didn’t seem to be the problem.)

Chris is looking into this. It turns out that the Glossary was a special case (if glossary and only one chapter, then don’t show chapter selector). The developers are considering doing this for all of the paratextual books (INT, BAK, etc.).