Add some comments

h2/src/main/org/h2/expression/aggregate/WindowFrame.java

@@ -521,7 +521,7 @@ public final class WindowFrame {
             int startIndex, int endIndex, boolean reverse) {
         if (exclusion == WindowFrameExclusion.EXCLUDE_CURRENT_ROW) {
             if (currentRow < startIndex || currentRow > endIndex) {
-                // Nothing to do
+                // Nothing to exclude
             } else if (currentRow == startIndex) {
                 startIndex++;
             } else if (currentRow == endIndex) {
@@ -530,10 +530,13 @@ public final class WindowFrame {
                 return biIterator(orderedRows, startIndex, currentRow - 1, currentRow + 1, endIndex, reverse);
             }
         } else {
+            // Do not include previous rows if they are not in the range
             int exStart = toGroupStart(orderedRows, sortOrder, currentRow, startIndex);
+            // Do not include next rows if they are not in the range
             int exEnd = toGroupEnd(orderedRows, sortOrder, currentRow, endIndex);
             boolean includeCurrentRow = exclusion == WindowFrameExclusion.EXCLUDE_TIES;
             if (includeCurrentRow) {
+                // Simplify exclusion if possible
                 if (currentRow == exStart) {
                     exStart++;
                     includeCurrentRow = false;
@@ -543,7 +546,7 @@ public final class WindowFrame {
                 }
             }
             if (exStart > exEnd || exEnd < startIndex || exStart > endIndex) {
-                // Nothing to do
+                // Empty range or nothing to exclude
             } else if (includeCurrentRow) {
                 if (startIndex == exStart) {
                     if (endIndex == exEnd) {

h2/src/tools/org/h2/build/doc/dictionary.txt

@@ -797,6 +797,6 @@ xym normalizes coord setz xyzm geometrycollection multipolygon mixup rings polyg
 pointzm pointz pointm dimensionality redefine forum measures
 mpg casted pzm mls constrained subtypes complains
 ranks rno dro rko precede cume reopens preceding unbounded rightly itr lag maximal tiles tile ntile signify
-partitioned
+partitioned tri
 
 discard enhancements nolock