The ISBD systempreferences are used to configure the ISBD views in OPAC and staff and also the ISBD download format. The default ISBD system preferences contain <br> tag for nicer display in the OPAC. these won't translate to newlines in the download and <br> will be printed.
Caused by: commit 792b0f764e1f0641b33ff3dbbe6f99e91109af9e Bug 13695: Add ISBD export option to OPAC (detail)
(In reply to Jonathan Druart from comment #1) > Caused by: > commit 792b0f764e1f0641b33ff3dbbe6f99e91109af9e > Bug 13695: Add ISBD export option to OPAC (detail) Well, 'caused' is relative, that bug allowed to download what we put there for ISBD output, not the <br/>. I suggest we use some 'verbatim' rendering in the opac-ISBD output, that keeps the newlines, so there's no need to put a <br/> at all.
The <br> come from the default data - a lot of people don't even know they can change that :)