(Sent quickly. Please excuse brevity.)

On 19/09/2011, at 11:51 PM, Bruno Le Floch <[log in to unmask]> wrote:

>> Oh yes, `\ \ \ \ ` would be pretty good. (My brain thought they'd be
>> concatenated for some reason and I didn't try it. Distracted by other work,
>> I suppose.)
> They're actually lost nowhere (e.g., not even after unfinished f-expansion)

Yeah, silly me. 

>> I'm probably happy to leave things as they are for now. In fact, any sort of
>> "indent" function would be better if it respected the line-wrapping routine
>> and that's more work than it's worth right now. I'll table this thought in
>> the Github wiki.
> Do you mean \msg_indent:n {<text to indent that may be line-wrapped>} ?

Aye :-)