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@@ -12,6 +12,14 @@ A particular bibliography in BibTeX format.
 * If not, move to a broader theme (something about "philosophy of gardening"
   goes to "philosophy" if there is no "gardening" theme available).
 
+## Non-standard fields
+
+Entries in this repository also uses the following non-standard BibTeX fields:
+
+* `tags`: used for non-hierarchical categorization. Example:
+
+        tags = {literature,theater,tragedy},
+
 ## Testing
 
     sudo apt install make biber pybtex