question about how to "expand" nested references in a bookmap

We've come across some bookmaps where some users are
expecting one thing and some are expecting another in
terms of how references expand in terms of nesting.

Does the DITA spec give an answer?  If not, does the TC
have an answer?

Here are two examples where each could be expanded in
(at least) two different ways:

Starting with a bookmap document:

bookmap

part  href=conceptA

part  href=conceptB

. . .

/bookmap

where conceptA includes two nested topics:

conceptA

body

conceptC

body

conceptD

body

/conceptA

How should these references get resolved?

Option #1:

RDS

bookmap

part as conceptA

body for conceptA

chapter for conceptC

body for conceptC

chapter for conceptD

body for conceptD

part as conceptB

body for conceptB

. . .

Option #2:

RDS

bookmap

part as conceptA

body for conceptA

conceptC

body for conceptC

conceptD

body for conceptD

part as conceptB

body for conceptB

. . .

(or something else).

Here is another example:

bookmap

chapter
href=mapA  format=ditamap

MapA

topicref  href=conceptE

topicref  href=conceptF

topicref  href=conceptG

How should these references get resolved?

Option #1:

RDS

Bookmap

conceptE

conceptF

conceptG

or Option #2:

RDS

bookmap

chapter for conceptE

chapter for conceptF

chapter for conceptG

(or something else).

paul