notes on inclusivity of cell intervals

user_manual/reference/PystencilsLanguageExtensions.md

@@ -29,13 +29,20 @@ All Python APIs are listed relative to `walberla.codegen.symbolic`.
     - Symbolic Functions
     - C++ API
 *   - Domain Axis-Aligned Bounding Box
-    - `domain.[xyz]_min()`, `domain.[xyz]_max()`
+    - `domain.[x|y|z]_min()`, `domain.[x|y|z]_max()`
     - `StructuredBlockForest::getDomain()`
 *   - Domain Cell Bounding Box (Current Refinement Level)
-    - `domain_cell_bb.[xyz]_min()`, `domain_cell_bb.[xyz]_max()`
+    - `domain_cell_bb.[x|y|z]_min()`, `domain_cell_bb.[x|y|z]_max()`
     - `StructuredBlockStorage::getDomainCellBB()`
 :::
 
+:::{note}
+Similar to `CellInterval::max()` in the C++ API,
+`domain_cell_bb.[x|y|z]_max()` refers to the largest valid cell index in the domain.
+Therefore, a comparison with `<=` (instead of `<`) is necessary
+in order to check if a cell is inside the domain.
+:::
+
 ### Block Geometry
 
 :::{list-table}
@@ -50,6 +57,10 @@ All Python APIs are listed relative to `walberla.codegen.symbolic`.
     - `StructuredBlockForest::getBlockCellBB()`
 :::
 
+:::{note}
+`block_cell_bb.[x|y|z]_max()` is *inclusive* to the block's cell bounding box;
+to check if a cell lies inside the block, use `<=` as a comparison operator.
+:::
 
 ### Cell Geometry