Ralph Cleminson wrote: 

> How about this?
> <titlePage>
>   <docAuthor>
>     <persName>PEHR KALMS</persName> 
>     <phr>Mag. Doc. in Hist. Nat. &amp; Oecon. vid *bo <lb/> 
> Academie, samt Ledamots af Kongl. <lb/>   Svenska Wetenskaps 
> Academien</phr>
>   </docAuthor>
>   <docTitle>
>     <titlePart type="main">W*STG*THA <lb/> Och <lb/> 
> BAHUSL*ND-<lb/>SKA RESA <lb/> F*rr*ttad <lb/> *r 1742.</titlePart>
>     <titlePart type="sub">Med Anm*rkningar uti Historia 
> Na-<lb/>turali, Physique, Medicine, Oeconomie,<lb/> 
> Antiquiteter etc.<lb/> Jemte n*dige Figurer.</titlePart>
>   </docTitle>
>   <docImprint>
>     <pubPlace>STOCKHOLM.</pubPlace>
>     Trykt hos <name>Lars Salvius</name><lb/>
>     P* des egen kostnad <date>1746</date>.
>   </docImprint>
> </titlePage>

It would be fine, if only I knew how to code in xslt that 
the text after the first <lb/> should be treated differently
than the text after the second <lb/>.

Using <seg> or <ab> (or <line>) seems good enough to me.
Thanks for all the input.