When using the Custom Formatted Reports — it is generally possible to create a call numbers list that can be used for printing. Please note, one challenge with labels is that label printers often have their own control sets, and I haven’t tested this process specifically against a set of label printers. If this proves to be something the community desires, I’ll look at how to add specific drivers/translators for printing to specified label printers.

Example Record:

=LDR  01392cam a2200325Ki 4500
 =001  99153751199003941
 =005  20190220161915.0
 =008  180727s2017\\sw\\\\\\000\1\perrd
 =010  \$a  2018371588
 =020  \$a9789163923609
 =020  \$a9163923602
 =035  \$a(OCoLC)1046449050
 =040  \$aZYU$beng$erda$cZYU$dOCLCF$dDLC
 =043  \$aa-ir---
 =050  \4$aBP189$b.N84 2017
 =100  1\$6880-01$aNuhʹrūdī, Riz̤ā,$eauthor.
 =880  1\$6100-01//r$aنه‌رودى، رضا‎
 =245  10$6880-02$aSīrat-i ān rūy-i sikkah :$bḥaqīqat-i jamāl-i ṣūrat va kamāl-i sīrat-i ādamʹhā /$cnivīsandah va shāʻir: Riz̤ā Nuhʹrūdī (mansūb bih Ḥaqqʹbīn)
 =880  10$6245-02//r$aسىرت آن روى سكه :‎$bحقىقت جمال صورت و کمال سىرت آدمه‌ا /‎$cنوىسنده و شاعر: رضا نهر‌ودى (منسوب به حقب‌ىن)‎
 =250  \$6880-03$aChāp-i nakhust.
 =880  \$6250-03//r$aچاپ نخست.‎
 =264  \1$aSolna (Sweden) :$bArash Förlag, 2017.
 =300  \$a350 pages ;$c21 cm
 =336  \$atext$2rdacontent
 =337  \$aunmediated$2rdamedia
 =338  \$avolume$2rdacarrier
 =546  \$aIn Persian.
 =650  \0$aMysticism$xIslam.
 =650  \7$aMysticism$xIslam.$2fast$0(OCoLC)fst01031643
 =880  \1$6264-00$aسوئد [Sweden] :‎$bانتشارات آرش،‎$c‪2017‬.

To output a label, pulling from the 050 where the label format is up to 11 lines — the format would look like the following:

BP
189
.N84
2017

You would use the following:

{050$a}.regex("([^0-9]*)(.*)","$1\n$2")
{050$b}.regex("([^\s]*)( )(.*)", "$1\n$3") 
{lines}.pad(11)

Above, you can see the arguments list uses the .regex syntax and then finishes with the {lines} mnemonic with the .pad function that tells the program that all blocks should have a total of 11 lines.