What is na4zi4pang2 (pinyin) in the decomposition of na4 (那)? The New Practical Chinese Reader introduces the following decomposition: na4 (那) = na4zi4pang2 + yi4 (阝).

I understand that 阝 represents radical 163 (yi4).

Na4zi4pang2 (pinyin) looks close to radical 74 (yue4, 月), but only close. It apparently is not a proper Chinese word or phrase that can be looked up in a dictionary.

My current guess that it is an arbitrary construct for a situation where one of the basic constituents of a composite character is not another basic character nor a radical, yet something that is also made up of strokes, and that the pinyin name is the concatenation of stroke names.

Could an expert and/or native speaker please confirm or otherwise clarify. I'm especially interested whether such constructs have Unicode font representations (and what the Unicode representation U+xxxx of na4zi4pang2 would then be).
There is no  radical, but the left part of 那 can be

冄 rǎn (the same as 冉)
U+5184
Seal Script


That's because in the seal script, 那 is written as


The left part is 冄, and the right part (radical) is 邑. So in 說文解字, it is described as

从邑，冄聲。


But it is better not to call 冄 a &quot;radical&quot;, because modern dictionaries and older dictionaries haven't listed it as a radical.
It is interesting in 康熙字典, 那 has these interchangeable characters:

 

But they are obsolete now, you should not use them.