Hello map people!

I am working on an article with Tim Kiser and Cathy Hodge on map
classification systems used by libraries and have a slight problem. As part
of the article, we're including a brief description of the classification
systems and how the call numbers work. So I know that for a topical map in
Dewey, the notation .022 is added to the base number for say 386 for a map
of ferry lines. That gives us a call number of 386.022 but how would I add
the extension to show that it's a map of ferry lines in Michigan? Would it
be 386.022774? None of us have worked with Dewey all that much and are
hoping that someone more familiar with the system can point us in the right
direction.

Many thanks!

Susan Moore
University of Northern Iowa
Cedar Falls, IA 50614
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