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packages/sheets-filter/docs/README.md

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+# Sheets Filter
+
+> There are a lot of implementation details that is not explicitly documented in the OOXML document or just simply hard to be noticed. This documents entails some interesting and important details.
+
+## Architecture Design
+
+Please refer to the excalidraw file in the same folder.
+
+## Details of Microsoft Excel
+
+The first detail that is interesting is 
+
+## History Tickets
+
+- [\[Feature Ticket\] Filter for Sheet](https://github.com/dream-num/univer/issues/1450)
+
+## Custom Filters
+
+### OOXML Compatibility
+
+In OOXML, there are a limited number of custom filter operators (please refer to `CustomFilterOperator`), and other operators including `startsWith` and `endsWith` (for a full list of this kind of operators see `ExtendCustomFilterOperator`) are actually supported by the combinations of OOXML operators, `*?` regex-like fuzzy matching, filter-by-values, dynamic filter, and so on.
+
+We take the same method instead of making `ExtendCustomFilterOperator` to be first-class citizens, because it is more OOXML-compatible and makes importing/exporting Excel files easier to implement.
+
+The cost is to implement the transformation between `ExtendCustomFilterOperator` and combinations. But the overall cost seems to be acceptable.
+