\book and \bookpart as output defs?

On 08/08/2026 13:50, David Kastrup wrote:
>> On 07/08/2026 15:45, David Kastrup wrote:
>>> bookA = \book { ... }
>>> bookB = \bookpart { ... }
>>>
>>> \book { \bookA ... }
>>>
>>> which would mean to create a book as an amended copy of \bookA
> bookA can just contain common headers and possibly a common introduction
> for a number of books (like solfeges for soprano, alto, tenor, bass).

Then why would it be enclosed in \book already? Surely the same could be 
achieved with smart use of variables and/or nesting includes.

I think I’m beginning to understand where you’re coming from. Is it that 
\book would work more like an output definition akin to \layout { 
\context {} } that can be defined once and modified any number of times? 
I have never seen it that way. Unlike contexts, \book{} environments 
aren’t named per se, are they?

Best, Simon

(other responses following)