Examples of 008/15-17 (Place of publication, production, or execution) when totally unknown:

008/15-17 xx#

260 ##$aS. 1. :$bs.n.,$c1983.

[Place is completely unknown.]

008/15-17 xx#

245 00$a[Hope diamond]$h[realia].

[Field 260 is not present in the record.]