Trade subject schemes like BISAC or Thema are used with a “main subject” – a single primary subject code. If Audience Codes are used to create broad categories of books their creators would expect to see subjects appropriate to their selected category.
For BISAC Subjects:
Books identified for Children/juvenile or Young adult MUST be supported by appropriate BISAC Subjects lists for Juveniles or Young Adults
Books intended for Adults (Trade books) MUST be supported by appropriate subjects from the non-BISAC subjects and NOT include any Juvenile or Young Adult subject listscodes.
No one says this is a perfect way to do things, but professionals actually know what they are doing and allowances are made — particularly for YA novels as cross-over products for adults. Also be aware that BISAC Subjects are created so that all subjects are isolated to a single Audience category within the scheme – mixing should NOT happen Thema is less structured in terms of mixing categories of codes to create a subject picture, so the Audience category association would apply to the main subject only. .
For Thema Subjects:
- The Thema Main subject code must be match the audience code (juvenile codes for juvenile or YA books) and be usable to create the broad differentiation for Fiction vs Non-fiction
BISAC has guidelines in it's PDF or Word version and Thema has an excellent guide as well as worked examples. Please refer to documentation for each subject scheme for more information using it properly.
Juvenile books (both Children's and Young Adult titles) must be supported by Audience Range information. If there are any points to be emphasized here it is that:
Grade Ranges (US or Canada are considered equivalent) can highlight that book has potential for classroom use. A grade ranges range doesn't correspond to any specific curriculum assessment so they are still generic and best supported by other types of documentation that provide curriculum support