Oboronni zamky zakhidnoho Podilli︠a︡ XIV – XVII st. : (istorychno-arkheolohichni narysy) / I︠U︡khym Sit︠s︡insʹkyĭ. (OCLC #32649823)

This title is about castles and fortifications in a city in Ukraine:

650 _0 ǂa Fortification ǂz Ukraine ǂz Podillia.
650 _0 ǂa Castles ǂz Ukraine ǂz Podillia.

The LC classification NA1455.A-Z is for Architecture of special countries—Europe with NA1455.U47 specifically being for Ukraine. This class number is subarranged using Table N15, which includes the somewhat cryptic:

.x2A-x2Z   Local, A-Z

This means that to specify a narrower location than Ukraine, append 2 to Ukraine’s cutter, and add a second cutter for that location (Podilla):

050 _4 ǂa NA1455.U472 ǂb P6357 1994

As a local practice, we always use the publication year in monograph call numbers when possible.