In what order should BISACs be assigned?

Publishers should assign BISACs in order of increasing importance. The least important BISAC should be assigned first; the most important, last.

Sample Data:

name	isbn	bisacs
The Science of a Carve Turn	9781633625808	JNF051140; JNF054110; JNF054160

After ingestion of the sample data, the BISACs appear in TitleLeaf (product page, bisac assignment section) in the following order:

JUVENILE NONFICTION / Science & Nature / Physics (JNF051140)
JUVENILE NONFICTION / Sports & Recreation / Olympics (JNF054110)
JUVENILE NONFICTION / Sports & Recreation / Winter Sports (JNF054160)

See screenshot:

TitleLeaf, Assigned BISACs, Order

The resultant ONIX feed illustrates the importance given to the last assignment:

<BASICMainSubject>JNF054160</BASICMainSubject>
<Subject>
  <SubjectSchemeIdentifier>10</SubjectSchemeIdentifier>
  <SubjectCode>JNF051140</SubjectCode>
</Subject>
<Subject>
  <SubjectSchemeIdentifier>10</SubjectSchemeIdentifier>
  <SubjectCode>JNF054110</SubjectCode>
</Subject>